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I 



THE IDENTIFICATION 
OF ORGANIC X , 
COMPOUNDS - 

By 
G. B. NEAVE, M.A., D.Sc. (St. Andrews) 

and 
I. M. HEILBRON, Ph.D. (Leipzig), F.I.C. 

LECTURERS AND DEMONSTRATORS, DEPARTMENT 

OF CHEMISTRY, GLASGOW AND WEST OF 

SCOTLAND TECHNICAL COLLEGE 




LO 

CONSTABLE & CO., LIMITED 
1911 



BUTLER & TANNER 

THE SELWOOD PRINTING WORKS 

FROME AND LONDON 



Preface 

IN teaching practical organic chemistry we have 
found the want of a convenient text-book dealing 
with the identification of simple organic compounds, 
such as is required by students working for the Inter- 
mediate and Final (Branch d) Examinations of the 
Institute of Chemistry. Moreover, many of the 
reactions and physical constants are not easily acces- 
sible, but are only to be obtained by a diligent and 
often tedious search through some of the larger books 
of reference. 

In this small volume we have endeavoured to 
bring together in a convenient form the principal 
reactions and physical constants of the most import- 
ant organic substances. Our aim has been to elimin- 
ate, as far as possible, guess-work on the part of the 
student, and to provide him with methods by which 
he can readily detect the more important groups in 
the compound, assign it to its class, and then com- 
plete its identification by referring to the section 
dealing with the class to which it belongs. Wherever 



288249 



iv PREFACE 

possible, an easily prepared derivative is described 
under each compound. 

In many cases descriptions of operations are brief, 
as we assume that the student has already attended 
lectures on Organic Chemistry and worked through 
a satisfactory course of Preparations. 

The scheme adopted in this book having given 
satisfactory results in the laboratories of this College, 
we now venture to give it wider publicity. 

We are deeply indebted to Professor G. G. Hen- 
derson for the interest he has taken in the work, and 
for a number of valuable suggestions. 

G. B. N. 

I. M. H. 

GLASGOW, 

April, 1911. 



Contents 

SECTION PAGE 

I PRELIMINARY TESTS .... 1 

II TESTS FOR THE ELEMENTS ... 4 

III GROUP REACTIONS .... 8 

IV HYDROCARBONS 14 

V ALCOHOLS ...... 19 

VI ETHERS 22 

VII PHENOLS 23 

VIII ALDEHYDES .29 

IX KETONES 36 

X ACIDS . 38 

XI AROMATIC SULPHONIC ACIDS ... 48 

XII ACID ANHYDRIDES . . . .52 

XIII ACID HALIDES 53 

XIV ACID AMIDES 53 

XV ACID IMIDES 55 

XVI ACID ANILIDES . . . . .55 

XVII ESTERS. 56 

vii 



viii CONTENTS 

SECTION PAGE 

XVIII QUINONES 58 

XIX CARBOHYDRATES ..... 60 

XX GLTJCOSIDES . . . . . .61 

XXI AMINES 62 

XXII NITRO COMPOUNDS .... 68 

XXIII NITROSO COMPOUNDS .... 72 

XXIV NlTRILES AND ISONITRILES . . . 74 
XXV ISOCYANATES. . . . . .75 

XXVI UREAS AND UREIDES . . . .75 

XXVII URIC ACID GROUP .... 78 

XXVIII HALOGEN COMPOUNDS . . . .80 

XXIX Azo COMPOUNDS . . . . .83 

XXX PYRIDINE AND QUINOLINE GROUP . . 85 

XXXI ALKALOIDS . . . . . .86 

XXXII SULPHUR COMPOUNDS . . . .89 

XXXIII TERPENES AND ALLIED COMPOUNDS . 94 

XXXIV ALBUMINS AND PROTEIDS . . .97 
APPENDIX ... . . .99 

INDEX . 101 







I. PRELIMINARY TESTS. 

1. ORGANIC compounds are often characterized 
by their appearance and smell, and the experienced 
student may frequently be able to classify and in 
some cases to identify a substance by means of these 
physical properties. 

Colour is generally induced in a compound by the 
presence of the following common groups : 

(a) Nitro group. The compound is then gener- 
ally yellow. 

(6) Nitroso group. The compound in the fused 
state or in solution (if monomolecular) is blue to 
green in colour. 

(c) Azo group and other such related groups. 
The compound is generally highly coloured. 

(d) Compounds having a quinonoid structure are 
usually strongly coloured. The common quinones 
are all deep yellow. 

2. If the substance is a solid, a small quantity is 
heated on platinum foil and the changes which occur 
are carefully noted. 

(a) A sooty flame indicates a high percentage of 
carbon in the substance. The compound is then 
probably one of the aromatic series. 





2. : ... THE IDENTIFICATION OF 

, t (6J An ihcpmbu'stible residue indicates the pres- 
ence .bt ''a* m&tai *r*r some inorganic matter in the 
compound, which is then tested for in the usual 
manner. 

It must be remembered, however, that the metals 
Mercury and Arsenic, likewise Ammonium salts, are 
volatile. 

3. The solubility of the substance in water is 
tested. 

(a) With the exception of certain salts, substances 
containing hydroxyl radicles usually dissolve. 

(6) The following classes of compounds are also 
generally soluble : Lower alcohols, aldehydes, 
ketones, monobasic acids, polybasic acids, substi- 
tuted acids, carbohydrates (except starch and 
cellulose), lower amines and amides, urea and its 
homologues, thioureas, cyanates, alkyl sulphates. 

(c) The solution is tested with litmus. 

(i) An acid reaction indicates the presence of a 
carboxyl or sulphonic group in the substance. A 
salt of a weak base would be hydrolytically dissoci- 
ated in dilute solution with a resulting acid reaction. 

Acid chlorides are rapidly, acid anhydrides slowly, 
decomposed by water, especially on warming. 

(ii) An alkaline reaction usually indicates the 
presence of a free base. 

4. A small quantity of the substance (about 
0-25 gram) is heated with a large excess of soda-lime 
in a hard glass test-tube fitted with a cork and a, 
short right-angled delivery tube, 



ORGANIC COMPOUNDS 3 

(a) Many nitrogen compounds evolve ammonia. 
An amine is liberated from an amine salt. 

(6) Formates are decomposed with evolution of 
hydrogen. 

(c) Hydrocarbons are produced frw. carboxy 
acids or their salts. \ 

(d) Phenols are formed from hydroxy aromatic 
acids or their salts. 

(e) A smell of burnt sugar is observed from carbo- 
hydrates, 'glucosides and many higher acids such as 
citric acid, tartaric acid, malic acid, tannic acid 
and gallic acid. 

5. The substance is warmed with concentrated 
caustic soda solution. NS V^^ 

(a) Ammonia is evolved from ammonium salts ? 
amides, and imides. 

(6) Amines are liberated from their salts. The 
lower aliphatic amines have characteristic ammonia - 
cal fishy odours and are inflammable. The aromatic 
amines are insoluble oils or solids. 

(c) Acetyl derivatives of amines are decomposed, 
liberating the free amine. The decomposition is 
only accomplished by prolonged heating. 

(d) Esters are slowly hydrolysed with liberation 
of the alcohol. The vapours of the lower alcohols 
are inflammable. The pleasant characteristic odour 
of the ester disappears. 

(e) Acids, phenols and nitrophenols dissolve with 
formation of a salt. The nitrophenols give red or 
yellow solutions. 

(/) Alkaloids are precipitated from solutions of 



4 THE IDENTIFICATION OF 

their salts. Morphine is only slowly precipitated 
from a solution of its salt and is readily soluble in 
excess of the reagent. 

(g) Aliphatic aldehydes, with the exception of 
formaldehyde, are converted into resins. 

(h) Solutions of glucose and lactose are turned 
brown. 

6. Dilute sodium carbonate solution is added to 
a small quantity of the substance contained in a 
test-tube, and the mixture is gently warmed. 
Acids, chlorophenols, nitrophenols and polyhydric 
phenols readily dissolve. Monohydric phenols are 
insoluble. 

7. In order to ascertain if the substance is a 
saturated or unsaturated compound, a small quan- 
tity is dissolved in chloroform or in some suit- 
able solvent having no action on bromine and a 
dilute solution of bromine in the same solvent is 
added, drop by drop. If the bromine is instantly 
decolourized without a simultaneous evolution of 
hydrobromic acid, the presence of a double or treble 
bond is shown, the substance being unsaturated. 



II. TESTS FOR THE ELEMENTS. 

Oxygen cannot be detected by any direct test, and 
the indications of its presence in a substance must 
be inferred from the foregoing experiments. 



ORGANIC COMPOUNDS 5 

It is not generally necessary to make any special 
tests for Carbon and Hydrogen. 

The presence of Nitrogen in an organic substance 
is indicated by heating a small quantity of the com- 
pound in a hard glass test-tube with excess of soda- 
lime. If ammonia is evolved, the presence of 
nitrogen is proved. 

As, however, nitro-compounds, azo-compounds 
and some other nitrogen compounds do not respond 
to this test, the following delicate test must be applied 
before the absence of nitrogen may be considered 
conclusively proved. 

A small piece of sodium, about the size of a pea, 
is dropped into a dry hard glass test-tube and gently 
warmed till it melts, after which a little of the sub- 
stance, about 0-1 gram, is introduced in such a 
manner that it falls directly on the sodium. If the 
substance is a liquid it is allowed to fall drop by 
drop on the sodium, care being taken to prevent 
it touching the sides of the tube. After the first 
violent action has ceased, the tube is heated in a 
Bunsen flame till all apparent change is over. 

The tube is allowed to cool and 10 cc. water are 
carefully added. The mixture is boiled for a few 
minutes and, if necessary, filtered from any carbon- 
aceous matter. 

If the filtrate be divided into three portions the 
presence of a halogen or of sulphur in the substance 
may also be directly tested. 

One portion of the original solution or filtrate is 
now treated with a few drops of caustic soda solu- 



6 THE IDENTIFICATION OF 

tion, a little freshly-prepared ferrous sulphate solu- 
tion and finally a few drops of ferric chloride solu- 
tion, and the whole well shaken. On carefully 
acidifying with concentrated hydrochloric acid a 
blue solution or precipitate of Prussian blue is 
formed, proving the presence of nitrogen in the 
original substance. 

Note. With substances containing only a small 
percentage of nitrogen a greenish-blue solution is 
frequently obtained which may only show the 
Prussian blue precipitate after standing for a con- 
siderable time. 

The formation of the Prussian blue depends on the 
fact that the nitrogen and carbon combine with the 
sodium to yield sodium cyanide. This compound in 
presence of ferrous hydroxide combines to give 
sodium ferrocyanide 

Fe(OH) 2 + GNaCN =Na 4 FeC 6 N 6 +2NaOH 

After the addition of ferric chloride and acid the 
insoluble Prussian blue is precipitated 

3Na 4 FeC 6 N 6 + 4FeCl 3 =Fe 4 (FeC 6 N 6 ) 3 + 12NaCl. 
After testing the one portion for the presence of 
nitrogen another portion is acidified with nitric acid, 
the solution boiled to expel any hydrocyanic acid 
present, and then silver nitrate solution is added. 
If a precipitate is formed the presence of a halogen 
in the original substance is indicated and its nature 
may be determined by submitting the precipitate 
to the usual examination for the detection of cMorine, 
bromine, or iodine. This test depends on the 



ORGANIC COMPOUNDS 7 

formation of sodium halide produced by combination 
of any halogen in the original substance with the 
metallic sodium. 

Another simple test to prove the presence of 
a halogen in a substance is obtained by wrapping 
a small piece of copper oxide within a stout 
copper wire, heating it in a Bunsen flame until 
no green colouration is produced, and allowing it 
to cool. A very small quantity of the substance 
is then placed on the oxide, which is again heated 
in the flame, when, if a halogen be present, a green 
colouration is observed, due to the formation of a 
volatile halogen compound of copper. This test 
is not absolutely conclusive, as some non-halogen- 
compounds appear able to produce a similar coloura- 
tion. Further, by this test, no information is 
obtained as to which halogen is present. 

Sulphur in a compound is best detected by taking 
the third portion from the sodium extract as already 
described, and placing a drop of the alkaline solution 
on a silver coin. If the original substance contained 
sulphur, sodium sulphide will have been produced, 
forming on the silver coin a black precipitate of 
silver sulphide. 

The presence of sodium sulphide in the alkaline 
filtrate is also readily detected by the addition of 
sodium nitroprusside solution, which produces a 
deep violet colouration with an alkali sulphide. 

Phosphorus may be detected by fusing a small 
quantity of the substance with a mixture of equal 
portions of potassium nitrate and carbonate on a 



8 THE IDENTIFICATION OF 

piece of platinum foil. The residue is dissolved in 
water, acidified with a few drops of concentrated 
nitric acid and a phosphate tested for in the usual 
way with ammonium molybdate. 



III. GROUP REACTIONS. 

FROM the foregoing preliminary tests the student 
will have deduced the type of compound with which 
he is dealing, or at any rate something of its nature. 
The following tests for individual groups may now 
be performed : 

, HYDROXYL GROUP. 

(a) A small quantity of the compound is heated 
for about fifteen minutes with an excess of acetic 
anhydride. 

If a hydroxyl group is present an acetyl derivative 
(oily or crystalline) is thus formed which may 
then be separated, washed with dilute sodium car- 
bonate solution and finally hydrolysed by heating 
under a reflux condenser with caustic soda solution. 
The acetyl compound is, in this way, decomposed 
with formation of an acetate which can readily be 
recognized by applying the usual tests for acetic 
acid or acetates (see page 38). 

(b) SCHOTTEN-BAUMANN REACTION. About 1 



ORGANIC COMPOUNDS 9 

gram of the compound is vigorously shaken up 
with about 1 cc. benzoyl chloride and sufficient 
dilute caustic soda solution to render the mixture 
alkaline. The product is poured into water and 
the crystalline benzoate separated by filtration, 
washed with water and then hydrolysed with caustic 
soda solution. After hydrolysis an alkali benzoate 
is formed, which can be detected in the usual manner 
(see page 41). 

If required, the benzoyl derivative may be puri- 
fied by recrystallization from alcohol, and its 
melting point determined. 

METHOXY AND ETHOXY GROUPS. 

Seven cc. hydriodic acid (Sp. Gr. 1-7) are added 
to about -2 gram of the compound in a test-tube 
fitted with cork and delivery tube, the end of which 
dips into an alcoholic solution of silver nitrate. 
The mixture is very gently heated in a glycerine 
bath to 140 and, if a methoxy or ethoxy group be 
present, methyl or ethyl iodide distils over and 
produces a precipitate of silver iodide in the alcoholic 
silver nitrate solution. 

ALDEHYDE GROUP. 

(a) TOLLEN'S REACTION. Ammonium hydroxide 
solution is cautiously added to about 2 cc. silver 
nitrate solution until the precipitate which is first 
formed is just redissolved. One cc. caustic soda 
solution is next run in and then 2 or 3 drops of 



10 THE IDENTIFICATION OF 

the supposed aldehyde solution. If an aldehyde 
group is present an immediate deposit of metallic 
silver is produced in the cold. 

(6) SCHIFF'S REACTION. A few drops of the 
aldehyde are poured into about 5 cc. of a solution 
of Schiff 's reagent (magenta solution which has been 
decolourized by sulphur dioxide). The red coloura- 
tion of the magenta is immediately restored. 

It should be noted that some ketones if present 
in large quantity react similarly, although the 
reappearance of the colour is more gradual and 
shows first after the mixture has stood for some 
time. 

(c) Fehling's solution is rapidly decomposed 
with precipitation of red cuprous oxide on being 
warmed with an aliphatic aldehyde. 

Aromatic aldehydes do not give this reaction. 

(d) If about 1 cc. of an aliphatic aldehyde is 
warmed with 2 cc. concentrated caustic potash 
solution, a brown precipitate of aldehyde resin 
separates out. 

Formaldehyde and aromatic aldehydes do not 
react in this manner, but yield mixtures of alcohols 
and acids, both containing the same number of 
carbon atoms as the original aldehyde. 

2R-CHO +KOH = R-CH 2 OH +R-COOK. 

(e) If 1 cc. of an aldehyde is vigorously shaken up 
in a test-tube with a few cc. of a cold saturated solu- 
tion of sodium hydrogen sulpnite l a precipitate 

1 See Appendix, page 100. 



ORGANIC COMPOUNDS 11 

of the aldehyde " bisulphite compound " is formed. 
Sodium carbonate solution liberates the aldehyde 
from the acid sulphite compound. 

Some ketones produce similar crystalline com- 
pounds. 

KETONE GROUP. 

If an aldehyde group is absent the presence of a 
ketone group may be confirmed by the preparation 
of the semicarbazone of the ketone (see page 
30 for this preparation). 

AMINO GROUP. 

(a) CARBYLAMINE TEST : About 0-1 gram of the 
substance is mixed with 3 drops of chloroform and 
2 cc. alcoholic potash, and the whole carefully 
warmed. The characteristic disgusting carbyl- 
amine odour is produced if the substance contains 
an amino group. 

(6) A small quantity of the compound is dissolved 
in a few cc. hydrochloric acid and sodium nitrite 
solution is then added until an excess of free nitrous 
acid is present. On warming, the amino group is 
converted into hydroxyl, with a vigorous evolution 
of nitrogen. 

Aliphatic amines and aromatic amines having the 
amino group in a side chain produce alcohols. 

Aromatic primary amines with the amino group 
in the. nucleus form phenols. 



12 THE IDENTIFICATION OF 

To distinguish between the two classes of aro- 
matic amines, the amine is diazotized (see page 64) 
in the cold, and a solution of /3-napthol in caustic 
soda added. An intensely coloured azo dye is 
produced if the amino group is in the nucleus. 

IMINO GROUP. 

If sodium nitrite is added to an acid solution 
of the compound, a yellow precipitate or solution 
of a nitrosoamine is formed, which may be con- 
firmed by applying LIEBERMANN'S TEST for nitro- 
soamines : 

The precipitate or solution containing the nitroso- 
amine is extracted with ether, the ethereal solution 
washed and dried rapidly over calcium chloride 
and the ether then blown off. To the residue, oil 
or solid, is now added a small quantity of phenol 
and 4 to 5 drops concentrated sulphuric acid, when 
a deep greenish black colouration is produced. On 
pouring the mixture into water a red solution is 
formed, which is changed to blue or green on addition 
of alkalies. 

Note. With aliphatic tertiary amines no reaction 
results on addition of nitrous acid, but dialkylani- 
lines interact readily, intensely coloured green 
nitroso compounds being formed, the NO-group 
displacing hydrogen of the benzene nucleus from 
the para position to the nitrogen atom. Substances 
of this type do not give Liebermann's reaction. 

The hydrochlorides of these para-nitroso bodies, 



ORGANIC COMPOUNDS 13 

which would be precipitated on addition of sodium 
nitrite to a hydrochloric acid solution of a dialkylani- 
line, are generally yellow in colour and must not 
be confounded with the secondary nitrosoamines. 

NITRO GROUP. 

A small quantity of the substance is mixed in a 
test-tube with about 2 cc. concentrated hydro- 
chloric acid and to this 1 gram zinc dust is gradually 
added in small quantities, and the mixture finally 
warmed. About 5 cc. water are now run in and 
then concentrated caustic alkali until the precipitate 
at first formed is redissolved. The amine produced 
is extracted with ether, and the presence of the 
amino group can be recognized by the tests given 
in the preceding paragraph. 

NITRILES AND ISONITRILES. 

(a) A small quantity of the substance is heated 
with 20 cc. concentrated hydrochloric acid under 
a reflux condenser. The reaction mixture is then 
made alkaline with caustic soda and heated. 

Ammonia is evolved from nitriles, whereas the 
isonitriles yield under the same conditions sodium 
formate and an amine. 

(6) MENDIUS' REACTION FORNrrniLES. 1 Nitriles, 
when reduced in a similar manner to that described 
for the reduction of nitro-compounds, yield amines 
which can readily be isolated and identified. 
1 See page 74, 



14 THE IDENTIFICATION OF 

AZO-GROUP. 

Azo dye-stuffs when vigorously reduced, yield 
amines, either simple or complex. About 1 gram 
of. the substance is treated with about 20 cc. of a 
concentrated solution of stannous chloride in hydro- 
chloric acid. Caustic soda solution is then added 
until the precipitate first formed is just redis- 
solved. Free amines are liberated which may 
be separated, and the usual tests for the amino 
group applied. 



IV. HYDROCARBONS. 

THESE are generally colourless liquids or solids, 
practically insoluble in water, soluble in alcohol 
and ether. The solubility in the last mentioned 
solvents decreases with increase in the molecular 
weight of the compound. 

ALIPHATIC HYDROCARBONS. 

%-Pentane, C 5 H 12 , is an exceptionally stable 
colourless liquid, boiling at 36-37. 
?&-Hexane, C 6 H 14 , boils at 69-70. 
n-Heptane, C 7 H 16 , boils at 97-98. 
^-Octane, C 8 H 18 , boils at 124. 



Isoprene, ^ TT 2 >C-CH=iCH2, is a colourless liquid 



ORGANIC COMPOUNDS 15 

boiling at 37, obtained by dry distillation of 
caoutchouc. Concentrated hydrochloric acid con- 
verts isoprene into a substance very similar to, if 
not identical with, caoutchouc. 

AROMATIC HYDROCARBONS. 

Benzene, C 6 H 6 , B.P. 80-81, M.P. 54. The 
pure hydrocarbon has a peculiar, not unpleasant 
smell. It is exceedingly stable towards oxidizing 
agents. 

If 1 gram of the hydrocarbon be added to a mix- 
ture of 3 grams concentrated sulphuric acid and 
2 grams concentrated nitric acid (Sp. Gr. 1-4), and 
the mixture warmed on a water-bath for about 
J hour at 60, nitro-benzene is obtained, and on 
cooling may be separated from the lower layer of 
acids, washed, dried and identified [(see page 70) 

C 6 H 6 +N0 2 -OH = C 6 H 5 N0 2 +H 2 0. 

Toluene, C 6 H 5 -CH 3 ,B.P. 110. Toluene on treat- 
ment with chromic acid yields benzoic acid. 

About 1 gram of the substance is heated under 
a reflux condenser with a mixture consisting of 2 
parts potassium dichromate, 3 parts concentrated 
sulphuric acid and 3 of water. After oxidation 
the solution is filtered while hot, when on cool- 
ing benzoic acid separates out and may be tested 
for as shown on page 41. 

o-Xylene, CJBT 4 boils at 142. With dilute 



potassium permanganate it yields phthalic acid. 



16 THE IDENTIFICATION OF 

A small quantity of the hydrocarbon is heated 
under a reflux condenser for some time with dilute 
alkaline potassium permanganate. The solution 
is then, if necessary, treated with sulphurous acid 
to remove excess of potassium permanganate, 
filtered off from the separated manganese dioxide 
and acidified. The acid is then extracted with 
ether, dried with calcium chloride and the tests for 
phthalic acid applied (see page 42). 

m-Xylene and p-Xylene, boiling points 139 and 
138 respectively, are distinguished from each other 
by the fact that the meta-compound is sulphonated 
in the cold with sulphuric acid, while the para- 
compound remains unchanged. 

Ethylbenzene, C 6 H 5 -Calls, boils at 134. Chromic 
acid oxidizes it to benzoic acid. 

Mesitylene, CeHgfCHs^l : 3 : 5, is an agreeably 
smelling liquid boiling at 163-164. With chromic 
acid mesitylene is decomposed into acetic acid. 

Cumene, C 6 H 5 CH(CH 3 ) 2 , is a colourless liquid 
boiling at 152-153. On oxidation with chromic 
acid or dilute nitric acid it is converted into benzoic 
acid. 

Cymene, C 6 H 4 < niJ ;LTj |.|, is a pleasant smell- 

^UhL(Ubi 3 )2(4) 

ing liquid boiling at 175. 

Diphenyl, C 6 H 5 -Cells, is a colourless, crystalline 
solid, melting at 71, B.P. 254 ; when oxidized 
with chromic acid it is converted into benzoic acid. 

Diphenylmethane, C 6 H 5 *CH 2 -Cells, is a crystalline 
solid, M.P. 26 '5, On oxidation with chromic acid 



ORGANIC COMPOUNDS 17 

x 

it is converted into benzophenone which may be 
extracted with ether and identified (page 37). 

Stilbene,C 6 H 5 'CH : CH'C 6 H 5j crystallizes in colour- 
less needles, M.P. 124-125. It is unsaturated and 
readily adds on two atoms of bromine forming 
stilbene dibromide, C 6 H 5 -CHBr-CHBr.C 6 H5, M.P. 
137. Oxidation with chromic acid or alkaline 
permanganate yields benzoic acid. 

Styrene, C 6 H 5 'CH : CH 2 , is a colourless liquid 
which boils at 145. It is oxidized to benzoic 
acid with chromic acid mixture. 

Phenylacetylene, C 6 H 5 'C = CH, is a colourless liquid 
boiling at 139-140. It yields a yellow copper 
compound when mixed with ammoniacal cuprous 
chloride solution. On oxidation with chromic 
acid, benzoic acid is obtained. 

Naphthalene, Ci H 8 , crystallizes in lustrous leaflets 
which melt at 80 and boil at 218. It has a char- 
acteristic smell, and is very volatile. On addition 
of a solution of the hydrocarbon in benzene to a 
solution of picric acid in the same solvent, a yel- 
low crystalline compound, naphthalene picrate, 
CioH 8 ,C 6 H 2 (N0 2 ) 3 OH melting at 149 separates 
out on standing. Naphthalene on boiling with 
dilute nitric acid is oxidized, yielding phthalic acid 
and carbon dioxide. 

Anthracene, Ci 4 H 10 , crystallizes in almost colour- 
less lustrous plates, possessing a beautiful violet 
fluorescence. It melts at 213, boils at 360. With 
picric acid it forms the molecular compound 
C 14 H 10 ,C6H 2 (N0 2 ) 3 OH which is deposited from 

c 



18 THE IDENTIFICATION OF 

benzene solution in ruby-red needles melting at 
138. 

Anthracene is readily oxidized to anthraquinone 
by dissolving the hydrocarbon in warm glacial acetic 
acid and adding to the solution about double the 
weight of chromic anhydride, and then boiling for a 
short time. The mixture is largely diluted with 
water, the anthraquinone filtered off, washed with 
dilute sulphuric acid, then with water and finally 
dried. M.P. 273. 

Phenanthrene, Ci 4 H 10 , forms colourless leaflets 
melting at 99. It is readily soluble in alcohol, 
while the isomeric anthracene is only sparingly 
soluble. 

It combines with picric acid to give a yellow 
compound, phenanthrene picrate, melting at 144. 
With chromic anhydride it yields phenanthra- 
quinone, M.P. 205. 

C 6 H 4 V 

Fluorene | y CH 2 , crystallizes in colourless 
C 6 H 4 / 

leaflets with a violet fluorescence. It melts at 113. 
The picrate obtained by mixing benzene solutions 
of fluorene and picric acid melts at 79-80. 



ORGANIC COMPOUNDS 19 

V. ALCOHOLS. 

THE common monohydric alcohols are, as a rule, 
colourless liquids (diphenyl and triphenyl carbinols 
are solids) with a neutral reaction and possessing a 
characteristic smell and taste. The lower members 
are soluble in water, but the solubility rapidly de- 
creases with increase of molecular weight. The 
Sp. Gr. is always less than that of water. 

The polyhydric alcohols are oily liquids or crystal- 
line solids, all readily soluble in water, sparingly 
soluble or insoluble in ether. 

PRIMARY MONOHYDRIC ALCOHOLS. 

Methyl alcohol, CH 3 OH, is a colourless, mobile 
liquid boiling at 66 '5. It burns with a bluish non- 
luminous flame. If a mixture of methyl alcohol 
with dilute sulphuric acid and potassium dichromate 
be distilled, the distillate contains formic acid 
which may be identified (page 38). 

When methyl alcohol is heated with salicylic 
acid and concentrated sulphuric acid, methyl 
salicylate is formed and can be identified by its 
odour. On warming methyl alcohol with para- 
nitrobenzoyl chloride, the methyl ester is formed, 
melting at 96. 

Ethyl Alcohol, C 2 H 5 OH, boils at 78. 

1 . When ethyl alcohol is mixed with a little dilute 
sulphuric acid and potassium dichromate and the 
mixture warmed, the alcohol is oxidized to acetalde- 



20 THE IDENTIFICATION OF 

hyde which can be recognized by its peculiar choking 
smell. 

2. The formation of lodoform serves as a delicate 
test for ethyl alcohol. 1 To a solution of alcohol a 
little sodium carbonate is added and the mixture 
warmed to about 60. To this is now added drop 
by drop, a strong solution of iodine in potassium 
iodide until, after shaking, the liquid remains faintly 
brown. lodoform separates out, having a char- 
acteristic odour and melting at 119. 

3. The para-nitrobenzoic-ester, 

C 2 H 5 OOC-C 6 H 4 -N0 2 , 

is readily obtained as a crystalline solid melting 
at 57. 

Propyl alcohol, C 3 H 7 OH, boils at 97-4. It is 
miscible in all proportions with water, but on addi- 
tion of calcium chloride and other easily soluble 
salts it separates out from its aqueous solution, 

Normal Butyl Alcohol, C 4 H 4 OH, is a liquid with an 
agreeable odour boiling at 117. 

Isobutyl Alcohol, 3 >CH-CH 2 OH, is a liquid 

possessing a fusel-oil odour. B.P. 108. 

Normal Amyl Alcohol, C 5 HuOH, is a liquid almost 
insoluble in water, boiling at 137. 

Allyl Alcohol, C 3 H 5 OH (CH 2 : CH-CH 2 OH), is a 
mobile liquid with a pungent odour, boiling at 
96-5. It has the properties not only of a primary 
alcohol, but also of an unsaturated compound. 
1 Acetone also gives the lodoform test. 



ORGANIC COMPOUNDS 21 

On distilling allyl alcohol with chromic acid, 
formic acid (page 38) distils over. 

Benzyl Alcohol, C 6 H 5 'CH 2 OH, is a colourless liquid, 
with a faint aromatic odour and boils at 206. It 
is sparingly soluble in water, readily in alcohol and 
ether. On oxidation with dilute nitric acid it 
yields first benzaldehyde and then benzoic acid. 

SECONDARY MONOHYDRIC ALCOHOLS. 

Isopropyl Alcohol (CH 3 -CHOH-CH 3 ), boils at 82- 
83. Oxidizing agents convert it into acetone. 

Diphenyl Carbinol, benzhydrol, (C 6 H 5 ) 2 CHOH, 
crystallizes in silky needles, very sparingly soluble 
in water, M.P. 67-68. The acetate melts at 41-42. 

TERTIARY MONOHYDRIC ALCOHOLS. 

Tertiary Butyl Alcohol, (CH 3 ) 3 COH, is a colourless 
solid melting at 25, boiling at 83-84. 

Triphenyl Carbinol, (C 6 H 5 ) 3 COH, M.P. 159. The 
acetate melts at 99. 

POLYHYDRIC ALCOHOLS. 

Ethylene Glycol, CH 2 OH-CH 2 OH, is a thick 
colourless liquid boiling at 197-198. When 
glycol is heated with solid caustic potash to 
250, hydrogen is evolved and potassium tfxalate 
formed which may be identified (see page 39). 

Glycerol, C 3 H 5 (OH) 3 , is a colourless, syrupy 
liquid with a sweet taste, insoluble in ether. 

When glycerol is heated with potassium hydrogen 

i 



22 THE IDENTIFICATION OF 

sulphate, or with phosphoric anhydride, acrolein 
is produced and may be identified by its pungent 
disagreeable odour. 

When a borax bead is moistened with glycerol 
and held near the outer edge of a Bunsen flame 
it gives a green colouration. 

The following are crystalline solids : 

Erythritol, C 4 H 6 (OH) 4 , M.P. 112. 

Oxidation with cone, nitric acid converts ery- 
thritol into oxalic acid. The tetra-benzoate melts 
at 186-187. 

Arabitol, CH 2 OH(CHOH) 3 CH 2 OH, M.P. 102. 

Mannitol, CH 2 OH(CHOH) 4 CH 2 OH, M.P. 166. 
The hexabenzoate melts at 124-125, the hexacetate 
at 119. 



VI. ETHERS. 

THESE are neutral, volatile liquids, practically 
insoluble in water and chemically very indifferent. 
They can be best identified by their boiling points. 

Ethyl Ether, (C 2 H 5 ) 2 0, B.P. 34-35. 

Normal Propyl Ether, (C 3 H 7 ) 2 0, B.P. 90-91. 

Anisol, C 6 H 5 '0'CH3 is an ethereal smelling liquid 
boiling at 154-155. Heated with concentrated 
hydriodic acid to 140 it decomposes into phenol 
and methyl iodide. 

Phenetol, CeH 6 -0-C 2 H 5 , boils at 172. 



ORGANIC COMPOUNDS 23 

Phenyl Ether, C 6 H 5 '0 'Celts, crystallizes in long 
needles and possesses a smell resembling geraniums. 
It melts at 28, boils at 252. It is not reduced on 
heating with hydriodic acid. 



VII. PHENOLS. 

THE phenols, with the exception of m-cresol are 
crystalline solids. They are of an acid nature, 
the hydrogen of the hydroxyl being readily sub- 
stituted by metals. The monohydric phenols are 
but sparingly soluble in water, the polyhydric 
phenols readily soluble. 

Phenol, CeHsOH, is a colourless crystalline solid, 
which gradually acquires a reddish colour, and 
deliquesces on exposure to air. It melts at 43, 
boils at 181; it dissolves in 15 parts water and gives 
a violet colouration in neutral solution with ferric 
chloride. 

When an aqueous solution of phenol is mixed 
with one -fourth of its volume of ammonia solution 
and then with a few drops of a bleaching powder 
solution, and gently warmed, a fine blue colour is 
produced, which soon disappears. 

Bromine water precipitates tribromophenol from 
solutions as an oil which soon crystallizes and melts 
.at 92. The crude tribromophenol may if necessary 
be purified by recrystallizing from alcohol. The 
benzoate melts at 69. 



24 THE IDENTIFICATION OF 

o-Cresol, C 6 H,< 3 M.P. 31. On fusion 



with potassium hydroxide, salicylic acid is formed. 
With picric acid, a picrate, 2C 7 H80,3C6H 3 N307, 
melting at 88 is obtained in orange yellow needles. 

ra-Cresol is liquid and boils at 202-203. Ferric 
chloride colours an aqueous solution of m-cresol 
deep blue violet. The benzoate melts at 54. 

p-Cresol melts at 36 and gives with ferric chloride 
a blue colouration. The benzoate melts at 71-72. 




Carvaerol, | is a thick oil boiling at 236- 

237. An alcoholic solution of carvacrol is coloured 
green on addition of ferric chloride. 

CH 3 

|0 



Thymol, melts at 50-51, and possesses 

k^OH 
C 3 H 7 

a pleasant aromatic odour. An aqueous solution 
of thymol treated with one half its volume of 
glacial acetic acid and one volume of concentrated 
sulphuric acid produces on warming a red violet 
colouration. 

a-Naphthol, Ci. H 7 OH, melts at 94, is practically 
insoluble in cold water, readily soluble in alcohol 
and ether. Bleaching powder solution produces 
a dark violet colouration. A naphthol picrate is 



ORGANIC COMPOUNDS 25 

produced, by mixing alcoholic solutions of the com- 
ponents, in orange needles melting at 189. 

a-Naphthol acetate melts at 46. 

PREPARATION OP ACETATE. One gram of the 
naphthol is boiled for about fifteen minutes with 
2 grams acetic anhydride. On pouring the product 
into water the crude acetate separates out. It is 
purified by recrystallization from a small quantity 
of water. 

a-Naphthol benzoate melts at 56. 

/3-Naphthol melts at 122. With ferric chloride 
a greenish colouration is produced in an aqueous 
solution of the naphthol, from which after some time 
a white flocculent precipitate is thrown down. 
/3-Naphthol dissolved in strong potassium hydroxide 
solution and treated with chloroform produces on 
warming to 50 a blue colouration which gradually 
becomes green and finally brown. /3-Naphthol 
acetate, C 10 H 7 OOC CH 3 , melts at 70. The ben- 
zoate melts at 107. 



Catechol (pyrocatechin), ^H^ melts at 



104. It reduces Fehling's solution on warming. 
With lead acetate a white precipitate is obtained. 
Ferric chloride produces in an aqueous solution of 
catechol an emerald-green colouration, which on 
addition of sodium bicarbonate becomes violet-red. 

Guaiacol, C 6 H 4 <^ H3 ^ melts at 31. Ferric 

chloride gives its alcoholic solution an emerald-green 
colour. 



26 THE IDENTIFICATION OF 



Resorcinol, C 6 H 4 , M.P. 118. Ferric 



chloride produces a dark violet colouration. If 
equal weights of resorcinol and phthalic anhydride 
are gently heated together in a test-tube a yellow 
melt is obtained, which, when dissolved in dilute 
caustic soda solution, produces a solution showing a 
fine green fluorescence (formation of fluorescein). 
Bromine water precipitates tribromoresorcinol, 
M.P. 111, from an aqueous solution of resorcinol. 
The dibenzoate melts at 117. 

Quinol (hydroquinone), C 6 H 4 <^ j: |*|, melts at 

169 and is readily soluble in water, alcohol and ether. 

With ferric chloride quinhydrone is readily ob- 
tained in beautiful metallic green crystals by adding 
ferric chloride to a concentrated solution of hydro- 
quinone in water. The solution becomes at first 
red and then rapidly darkens. 

The diacetate and the dibenzoate melt respec- 
tively at 123 and 199. 
,CH 3 (1) 

Orcinol, C 6 H 3 /-OH (3), M.P. 107, is easily soluble 

\OH (5) 

in water, alcohol and ether. On expo'sure to the air 
it becomes red. With ferric chloride a violet-black 
colouration is produced. Bleaching powder solu- 
tion produces a dark red colouration which soon 
changes to yellow. The diacetate melts at 25, 
the dibenzoate at 88. 

Pyrogallol, C 6 H 3 (OH) 3 1:2:3, melts at 132-133 



ORGANIC COMPOUNDS 27 

and is readily soluble in water, alcohol and ether. 
An alkaline solution of pyrogallol quickly absorbs 
oxygen from the air and becomes brown. An 
aqueous solution of pyrogallol is turned brown on 
addition of nitrous acid solution. The tribenzoate 
melts at 90. 

Phloroglueinol, C 6 H 3 (OH) 3 1:3:5, melts at 218 
on quickly heating. It is readily soluble in water, 
alcohol and ether. With ferric chloride a blue- 
violet colouration is obtained. The acetate melts 
at 105, the benzoate at 173. The trioxime melts 
at 43. 

ALCOHOL PHENOLS. 



Saligenin, C ' M ' R 86 > is 



readily soluble in boiling water, alcohol and ether. 
It dissolves in concentrated sulphuric acid with an 
intense red colour. With ferric chloride it gives 
a blue colouration. 



Anisyl Alcohol, CeH^* , melts at 45. 



Dilute nitric acid oxidizes it to anisic acid, M.P. 

185. 

HALOGEN PHENOLS. 

o-Chlorophenol, C 6 H 4 <^,, , has an unpleasant 

odour and boils at 175-176. 

m-Chlorophenol is obtained as crystals melting at 

28-5. 



28 THE IDENTIFICATION OF 

2>-Chlorophenol melts at 37. It possesses a faint, 
unpleasant odour. Fused with alkalies it gives 
resorcinol. 

o-Bromophenol is an unpleasant-smelling oil, boiling 
at 194-195. 

m-Bromophenol melts at 32-33. 

p-Bromophenol melts at 63-64. 

o-Iodophenol is obtained as needles, melting at 43. 
It is fairly soluble in hot water, readily soluble in 
alcohol and ether. By warming with nitric acid 
(Sp. Gr = 12) picric acid is formed. 

m-Iodophenol melts at 40. 

2>-Iodophenol forms long needles melting at 92. 
By boiling with nitric acid it is readily converted 
into picric acid. 

OH 




Trichlorophenol, melts at 67-68 and 

Cl 

has an acid reaction. With hydrochloric acid and 
potassium chlorate, chloranil (see page 59) is formed. 
Tribromophenol (2:4:6) melts at 95. The acetate 
recrystallized from alcohol melts at 82. 

AMINOPHENOLS 

-VTTT 

o-Aminophenol, C 6 H 4 <^: 2 , when pure is colour- 

less, but readily becomes brown. It melts at 170, 
and is somewhat sparingly soluble in water, Teadily 
in ether. The acetate melts at 150. 



ORGANIC COMPOUNDS 29 

p-Aminophenol melts with" decomposition at 184. 
With chromic acid it is readily oxidized to quinone. 
p-Aminophenol Methyl Ester (pp . anisidine) 

OPTT 1 1 ^ 

3 )* forms plates melting at 52-56. 



Phenacetin, C 6 H 4 <" 2 nTT . melts at 135. 



On hydrolysis with caustic soda it yields sodium 
acetate, and phenetidine, B.P. 244. 



VIII. ALDEHYDES. 

THE lower aldehydes are volatile liquids soluble in 
water and possessing a characteristic odour. The 
higher members of the series are solids, insoluble in 
water. 

In chemical properties the aldehydes are neutral 
substances, easily oxidized to corresponding acids, 
their ready oxidation by the salts of the noble metals 
being one of the characteristics of the aldehydes. 

All aldehydes form oximes with hydroxylamine, 
phenylhydrazones with phenylhydrazine and semi- 
carbazones with semicarbazide hydrochloride. As 
these derivatives can readily be obtained in the pure 
state and are generally solids, their preparation and 
melting-point determination serve as an aid in the 
identification of an aldehyde. 

PREPARATION OF AN OXIME. One gram of the 



30 THE IDENTIFICATION OF 

aldehyde dissolved in the least possible quantity of 
alcohol is treated with a slight excess of hydroxyl- 
amine hydrochloride dissolved in a little water. 
To this mixture is added the theoretical quantity of 
sodium hydroxide in concentrated solution. If any 
precipitate is now formed, alcohol or water, as may 
be necessary, is added to bring about complete solu- 
tion. The solution is then heated on a water-bath 
under a reflux condenser for from one to two hours. 
The reaction mixture is then poured into water, 
made faintly acid with acetic acid and the oxime 
extracted with ether, the ethereal solution dried, 
the ether distilled off and the oxime recrystallized 
from some suitable solvent. 

PREPARATION OF A PHENYLHYDRAZONE. One 
cc. phenylhydrazine is added to about 5 cc. water 
and sufficient acetic acid added, with vigorous shak- 
ing, to bring about complete solution. About 0-5 
gram of the aldehyde is now added (in solution if 
necessary) and the mixture vigorously shaken and 
very gently warmed. The phenylhydrazone separ- 
ates out and, if solid, is filtered off, washed with 
dilute acetic acid, dried on a porous plate or be- 
tween filter paper, and finally recrystallized from 
alcohol or benzene. 

PREPARATION OF A SEMICARBAZONE. One gram 
of the aldehyde, dissolved in the smallest possible 
quantity of alcohol is added to a solution containing 
2 grams semicarbazide hydrochloride dissolved in the 
minimum quantity of water. A cold alcoholic solu- 
tion containing 2 grams potassium acetate, best 



ORGANIC COMPOUNDS 31 

prepared by boiling the acetate with alcohol, is now 
added, and, if any precipitate forms, water or alcohol, 
as the case requires, is then carefully added until a 
clear solution is obtained. The mixture is then 
allowed to stand for some hours, the aldehyde semi- 
carbazone gradually separating out. 

The addition of a few drops of methyl alcohol (free 
from acetone) often accelerates the separation of 
the semicarbazone. The semicarbazone obtained is 
finally recrystallized from methyl or ethyl alcohol. 

Formaldehyde, H-CHO, is gaseous at the ordinary 
temperature and is usually met with in solution, the 
aqueous solution possessing a penetrating, suffocat- 
ing odour. When its aqueous solution is mixed with 
ammoniacal silver nitrate solution a silver mirror is 
obtained. 

Trioxymethylene (HCHO) 3 , is a crystalline com- 
pound which sublimes readily under 100. When 
strongly heated it is decomposed into pure gaseous 
formaldehyde. It is readily soluble in cold sodium 
hydroxide solution, insoluble in alcohol and ether. 

Aeetaldehyde, CH 3 -CHO, is obtained as a strongly- 
smelling suffocating liquid, boiling at 21 and miscible 
in all proportions with water. Boiling with potas- 
sium hydroxide solution produces the yellow-brown 
aldehyde resin. Aeetaldehyde combines readily 
with ammonia gas to give aldehyde ammonia, a 
colourless crystalline solid. Its phenylhydrazone 
melts at 99, the semicarbazone at 162, the oxime 
at 47. 

Para-aldehyde (C 2 H 4 0) 3 , boils at 124 and on dis- 



32 THE IDENTIFICATION OF 

tillation is completely converted into acetaldehyde. 
It gives none of the usual aldehyde reactions. 

Meta-aldehyde (C 2 H 4 0) 3 , is isomeric with para j alde- 
hyde. It is a crystalline solid which sublimes at 
112 without melting. On distillation with dilute 
sulphuric acid it breaks down into acetaldehyde. 
Like para-aldehyde it gives none of the aldehyde 
reactions. 

Aldol, CH 3 -CH(OH)CH 2 -CHO, is a syrupy liquid 
which decomposes at 135 into crotonaldehyde and 
water 

CH 3 CH(OH)CH 2 -CHO = CH 3 CH :CH-CHO+H 2 0. 
It is soluble in water and alcohol, and gives the 
usual aldehyde reactions. 

Acrolein, CH 2 : CHCHO, is a pungent-smelling 
liquid, boiling at 52-53. It is readily oxidized to 
acrylic acid. 

Crotonaldehyde, CH 3 -CH : CH-CHO, is an ex- 
tremely disagreeable-smelling liquid boiling at 104. 
The oxime melts at 119-120. 

Benzaldehyde, C 6 H 5 'CHO, is a pleasant aromatic 
smelling liquid, which boils at 179. It does not 
reduce Fehling's solution but gives most of the alde- 
hyde reactions. Its oxime melts at 35, the phenyl- 
hydrazone at 155, the semicarbazone at 214. 

o-Toluic Aldehyde, C 6 H 4 <5 , boils at 200. Its 



oxime melts at 48-49. 

ra-Toluic Aldehyde boils at 199. 

p-Toluie Aldehyde is a liquid with a pepper-like 
odour, boiling at 204. The oxime exists in two 



ORGANIC COMPOUNDS 33 

forms. The anti-derivative melts at 79, the syn- 
compound at 109. 

CHO 




2>-Cumic Aldehyde, Cuminol, | I is a pleasant, 

CH(CH 3 ) 2 

aromatic-smelling liquid, boiling at 237. Its oxime 
melts at 58. 

Cinnamic Aldehyde, C 6 H 5 -CH : CH-CHO, decom- 
poses on boiling. The phenylhydrazone melts at 
168. 

SUBSTITUTED ALDEHYDES. 

Chloral, CC1 3 CHO, is a colourless, pungent-smell- 
ing liquid boiling at 97-98. Concentrated alkali 
solutions decompose chloral even at ordinary temper- 
atures into chloroform and alkali formate 

CC1 3 -CHO + KOH = CHC1 3 + H-COOK. 
The oxime melts at 39-40. 

Chloral Hydrate, CC1 3 -CH(OH) 2 , melts at 57. 
It is readily soluble in water and alcohol. It does 
not show the usual aldehyde reactions. By shaking 
with concentrated sulphuric acid it is immediately 
converted into chloral. 

Bromal, CBr 3 - CHO, boils at 174. With alkalies 
it is decomposed into brompform and alkali formate. 

Bromal Hydrate melts at 53-54. 

Cl 
o-Chlorobenzaldehyde, CaH^^^^ , is a liquid, boil- 



ing at 213-214, with a strong odour. Its oxime 
melts at 75 (anti), the syn. derivative at 98-102. 



34 THE IDENTIFICATION OF 

m-Chlorobenzaldehyde is obtained in long prisms, 
melting at 17-18, boiling at 213. Oxime, M.P. 
70 (syn.). 

p-Chlorobenzaldehyde is a solid with an odour like 
benzaldehyde, melting at 47-48. 

OTTO 
o-Nitrobenzaldehyde, C 6 H 4 < , is obtained in 



the form of long, pale yellow needles, melting at 
44. It has an odour similar to that of benzalde- 
hyde, is readily soluble in alcohol and ether, sparingly 
in water. Concentrated aqueous sodium hydroxide 
converts it readily into o-nitrobenzoic acid and o- 
nitrobenzylalcohol. The oxime melts at 96. 

ra-Nitrobenzaldehyde melts at 58. It is fairly solu- 
ble in hot water, readily in alcohol and ether. The 
oxime melts at 118. 

p-Nitrobenzaldehyde melts at 106. With chromic 
acid it is converted into its corresponding acid. The 
oxime melts at 129. 



o-Nitrocinnamic aldehyde, C 6 H 4 ? : CH ' CHO ' 



melts at 127 and is soluble in hot water. 

ra-Nitrocinnamie aldehyde, M.P. 116. 

2>Nitroeinnamic aldehyde melts at 141. The 
oxime melts at 178-179. 



o-Aminobenzaldehyde, ^^< obtained in 



silvery leaflets melting at 39-40, readily soluble 
in alcohol and ether, sparingly in water. The 
acetyl derivative melts at 70, the oxime at 132, 



ORGANIC COMPOUNDS 35 

ra-Aminobenzaldehyde is a yellow amorphous sub- 
stance. The oxime melts at 88. 

p-Aminobenzaldehyde melts at 70-71. The hydro- 
chloride is obtained in red crystals. The acetyl 
derivative melts at 155, the oxime at 124. 

Salicylic Aldehyde, C 6 H 4 <^ Q |*j, is a pleasant- 
smelling oil, boiling at 196. On oxidation it yields 
salicylic acid. The acetyl derivative melts at 37, 
the oxime at 57. 

m-Hydroxybenzaldehyde melts at 104. The aque- 
ous solution is coloured deep violet with ferric 
chloride solution. The oxime melts at 87. 

^-Hydroxybenzaldehyde melts at 115-116 and sub- 
limes undecomposed. The aqueous solution is 
coloured faintly violet with fermp^chloride. The 
oxime melts at 65. 

Anisic Aldehyde, C 6 H 4 <5?-2 , ( !?, boils at 248. 
^UUfets (4) 

The oxime melts at 61. * 

/CHO (1) 
Protocatechuie Aldehyde, C 6 H 3 ^-OH (3), melts at 

\OH (4) 

153. Ferric chloride colours an aqueous solution 
of protocatechuic aldehyde green ; on addition of 
sodium carbonate the colour changes to violet and 
then to red. The oxime melts at 150. 

/VCHO (1) 

Vanillin, C 6 H 3 <J OCH 3 (3) has a pleasant, vanilla- 
NOH (4) 

like odour and melts at 80-81. It gives with ferric 



36 THE IDENTIFICATION OF 

chloride a blue colouration. The benzoate melts at 
75, the oxime at 117. 



Piperonal, C 6 -. 

\^ ^>CH 2 , has a pleasant helio- 

trope odour. It melts at 37. The oxime melts at 
110-112, the phenylhydrazone at 100. 

Closely related to the aldehydes themselves are 
the aldehyde ethers. These are liquids, sparingly 
soluble in water, which on boiling with dilute hydro- 
chloric acid are readily broken up into their consti- 
tuent aldehyde and alcohol. 

Methylal CH 2 (OCH 3 ) 2 , B.P. 42. 

Acetal, CH 3 -CH(OC 2 H 5 ) 2 , B.P. 104. 



4 

IX. KETONES. 



THE aliphatic ketones are liquids, the common aro- 
matic ketones are solids. They are only oxidized 
with difficulty and therefore do not reduce alkaline 
silver solutions. Only those ketones with a methyl 
group directly attached to the carbonyl group form 
bisulphite compounds. Like aldehydes they form 
oximes, phenylhydrazones, and semicarbazones. 
The methods for the preparation of these derivatives 
are similar to those employed in the case of the 
aldehydes. 

Acetone, CH 3 -CO-CH 3 , B.P. 56, is miscible with 



ORGANIC COMPOUNDS 37 

water in all proportions. With iodine and caustic 
potash it forms iodoform. The oxime melts at 
59-60. 

Methylethylketone, CH 3 -CO-C 2 H 5 , boils at 80-81. 
The oxime is an oil, the semicarbazone melts at 
135-136. 

Diethylketone, C 2 H 5 -CO-C 2 H 5 , B.P. 102-103. 

Dipropylketone, C 3 H 7 -CO-C 3 H 7 , B.P. 144. 



Pinacoline, CH 3 C'CO-CH 3 , is a peppermint- 



C 
/ 



smelling liquid boiling at 106. It forms no bisul- 
phite compound. The oxime melts at 74-75. 

Aeetophenone, C 6 H 5 -CO-CH 3 , melts at 20. With 
picric acid it gives a picrate, greenish-yellow crystals 
melting at 53. The oxime melts at 59. 

Benzophenone, C 6 H 5 -CO -Cells, melts at 48-49. 
The oxime melts at 139-140, the phenyl-hydra- 
zone at 137. 

Benzoin, C 6 H 5 -CHOH-CO-C 6 H5, melts at 137. 
It is converted into benzil by means of nitric acid. 
Fehling's solution is readily reduced by means of 
benzoin. The oxime melts at 151-152 (a-deriva- 
tive). 

Deoxybenzom, C 6 H 5 -0*3(00 -CeHg, melts at 60, 
The oxime melts at f?> the phenylhydrazone at 
116. 

Benzil, C 6 H 5 .CO-CO-C 6 H 5 , melts at 95. The 
dioxime melts with decomposition at 237. 



38 THE IDENTIFICATION OF 

X. ACIDS. 

To obtain the acid from a salt, the latter is dissolved 
in water (if it is insoluble, it is boiled with sodium 
carbonate and filtered), and the solution acidified. 
In many cases the acid will be precipitated ; if 
soluble in water it is extracted with ether, the 
ethereal solution dried and the ether distilled off. 
The physical and chemical properties of the acid 
are then determined. 

1. SATURATED ALIPHATIC MONOBASIC ACIDS. 

The lower members are liquids, soluble in water, 
the solubility decreasing with increase of molecular 
weight. The higher members are odourless solids, 
insoluble in water. 

Formic Acid, H-COOH, when anhydrous boils at 
101. By the action of concentrated sulphuric acid, 
carbon monoxide is evolved. Formic acid reduces 
solutions of silver and mercury salts. 

Acetic Acid, CH 3 -COOH, when free from water 
melts at 16-5, and boils at 118. The addition of 
ferric chloride to a neutral solution of an acetate 
produces a deep red colour, which on warming dis- 
appears, while a brown flocculent precipitate of basic 
ferric acetate is thrown down. 

When acetic acid is warmed with alcohol and con- 
centrated sulphuric acid, ethyl acetate is formed, 
which may be recognized by its pleasant fruity odour. 

Propionic Acid, C 2 H 5 -COOH, boils at 141. It is 



ORGANIC COMPOUNDS 39 

precipitated as an oil from aqueous solution by the 
addition of calcium chloride. The ethyl ester boils 
at 98-99. 

^Butyric Acid, CH 3 -CH 2 -CH 2 -COOH, boiling at 
162, has an extremely unpleasant odour. Its ethyl 
ester boils at 120. 

Isobutyric Acid, ^ 3 >CH-COOH, boils at 155 

and is insoluble in water. The ethyl ester boils at 
110. 

Palmitic Acid, CH 3 -(CH 2 ) 14 -COOH, melts at 62. 
The lead salt formed by adding lead acetate to a 
neutral solution of ammonium palmitate melts at 
112. 

Stearic Acid, CH 3 -(CH 2 ) 16 -COOH, melts at 69-2 
and the lead salt at 125. 



2. SATURATED ALIPHATIC POLYBASIC ACIDS. 

These acids are solids, and are soluble in water. 

COOH 
Oxalic Acid, | + 2H 2 0, melts at 98. When 

COOH 

acted on by concentrated sulphuric acid, carbon 
monoxide and carbon dioxide are evolved. Potas- 
sium permanganate reacts with oxalic acid, with for- 
mation of carbon dioxide and water. The calcium 
salt is insoluble in water and in acetic acid. The 
dimethyl ester, which can be prepared by boiling 
the anhydrous acid with methyl alcohol for about 
ten minutes, is a solid melting at 54. 



40 THE IDENTIFICATION OF 

POO1T 
Malonic Acid, CH 2 , melts at 132. On 



heating more strongly, it is decomposed into acetic 
acid and carbon dioxide. 

CH 2 -COOH 
Succinic Acid, | , melts at 185. When 

CH 2 -COOH 

a neutral solution of ferric chloride is added to a 
neutral solution of a succinate, a brown-red precipi- 
tate of basic ferric succinate is produced. Succinic 

CH 2 CO \ 
anhydride | ;Q melting at 119, is obtained 

CH 2 CO X 

by the action of acetyl chloride on the acid at 50. 
It is purified by recrystallizing from chloroform. 

> melting at 97-5, 

is converted into the anhydride (M.P. 56-57) by 
heating for some time. 



3. UNSATURATED ALIPHATIC ACIDS. 

Acrylic Acid, CH 2 :CH-COOH, boils at 140 and 
polymerizes. The lead salt crystallizes in fine 
needles. When acrylic acid is fused with potassium 
hydroxide, it is decomposed into potassium formate, 
potassium acetate and hydrogen. The ethyl ester 
boils at 101-102. 

Crotonic Acid, CH 3 -CH:CH-COOH, melting at 
71-72, when fused with potassium hydroxide pro- 
duces potassium acetate and hydrogen. Its ethyl 
ester boils at 142. 



ORGANIC COMPOUNDS 41 

Oleie Acid, CH 3 -(CH 2 ) 7 -CH : CH-(CH 2 ) 7 -COOH, 
melts at 14, and boils at 223 at 10 mm. The lead 
salt is soluble in ether and melts about 80. When 
oleic acid is shaken with nitrous acid, it is transformed 
into the isomeric Elaidie Acid, melting at 44-45. 

H -C COOH 

Fumarie Acid, || , sublimes at 

HOOC C -H 

200, without melting. When distilled with phos- 
phorus pentoxide, maleic anhydride (M.P. 60) is 
formed. By the action of bromine at 100 on fumaric 
acid, dibromsuccinic acid, melting at 255-256 with 
decomposition, is produced. 

H - C - COOH 

Maleic Acid, f] , melting at 130, is 

H - C - COOH 

converted into the anhydride (M.P. 60) by heating 
under diminished pressure at 100. 



4. AROMATIC ACIDS. 

Benzoic Acid, C 6 H 5 -COOH, melts at 121, and can be 
sublimed easily. It is practically insoluble in cold 
water, easily soluble in alcohol and ether. When 
heated with lime, benzene is produced. Ethyl 
benzoate (B.P. 213), a pleasant-smelling liquid, is 
easily formed by heat ing together benzoic acid, ethyl 
alcohol and a small quantity of concentrated sul- 
phuric acid. 

o-Toluie Acid, C 6 H 4 <, M.P. 102, is easily 



42 THE IDENTIFICATION OF 

soluble in hot water. Dilute nitric acid oxidizes 
it to phthalic acid. 

m-Toluie Acid, M.P. 110, is readily soluble in 
water. 

p-Toluic Acid, M.P. 176-177. The methyl ester, 
a strongly smelling solid, melts at 32. 

a-Naphthoie Acid, d H 7 -COOH, M.P. 160 and 

/3-Naphthoic Acid, M.P. 182 are converted into 
naphthalene by distillation with lime. When the 
a-compound is oxidized with chromic acid in glacial 
acetic acid, phthalic acid is produced. Methyl /3- 
naphthoate is a solid melting at 77. 

Phthalie Acid, C 6 H 4 <;OOH |, on heating forms 



phthalic anhydride (M.P. 128). When the latter 
is heated with phenol and a little anhydrous zinc 
chloride, phenolphthalein is produced 

2C 6 H 5 OH = H 2 + 



/C-C 6 H 4 OH 
C 6 H 4 ( /Q 

\co 

Phenylacetic Acid, C 6 H 5 -CH 2 -COOH, M.P. 76, is 
sparingly soluble in cold water. 

Hydrocinnaminic Acid, C 6 H 5 -CH 2 -CH 2 -COOH, M.P. 
48. 

Cinnamic Acid, C 6 H 5 -CH : CH-COOH, M.P. 133. 
The methyl ester melts at 33. 



ORGANIC COMPOUNDS 43 

5. SUBSTITUTED ACIDS. 

A. HYDROXY ACIDS. 

Glyeollic Acid, CH 2 OH COOH, melting at 78-79, 
when heated to 100 is converted into an anhydride, 
M.P. 128-130. 

Lactic Acid, CH 3 -CHOH-COOH,is a syrup, easily 
soluble in water and alcohol, difficultly soluble in 
ether. Hydriodic Acid reduces it to propionic acid, 
while at the same time free iodine is produced. The 
silver salt melts at 100. 

CHOH-COOH 
Malic Acid, , melts at 100. When 

CH 2 -COOH 

calcium chloride and alcohol are added to a neutral 
solution of a malate, calcium malate is precipitated. 

CHOH-COOH 
Tartaric Acid, | , melting at 168-170, 

CHOH-COOH 

is decomposed on heating strongly, with production 
of a smell of burnt sugar. Calcium chloride added 
to a neutral solution of a tartrate (but not of tartaric 
acid) precipitates calcium tartrate. When ammoni- 
acal silver nitrate solution is added to a neutral 
solution of a tartrate, a silver mirror is produced on 
warming. 

CH 2 -COOH 

Citric Acid, C(OH)-COOH + H 2 0, is easily soluble 

CH 2 -COOH 
in water and alcohol. It loses its water of crystalliz- 






44 THE IDENTIFICATION OF 

ation at 130, and melts at 153. When calcium 
chloride is added to a neutral solution of a citrate 
and the mixture heated for some time, calcium 
citrate is precipitated. 



Salicylic Acid, C 6 H 4 < OH melting at 155, is 

converted into phenol when it is heated with lime. 
Ferric chloride added to a solution of salicylic acid 
produces a deep violet colouration, which is not des- 
troyed by addition of acetic acid. Methyl salicylate, 
which has a characteristic odour, boils at 224. 

/OH (1) 

Protocateehuie Acid, C 6 H 3 4-OH (2), melts at 199*. 

\COOH(4) 

Ferric chloride added to a solution of the acid, pro- 
duces a green colouration, which, on addition of 
sodium hydroxide, changes to blue and finally to 
red. 

Gallic Acid, C 6 H 2 (OH) 3 -COOH + H 2 0, decom- 
poses at 220, into carbon dioxide and pyrogallol 
(see page 26). Ferric chloride produces a blue- 
black precipitate, soluble in hydrochloric acid but 
reprecipitated by ammonia. 

Tannic Acid is an amorphous powder, more 
soluble in water than in alcohol. Ferric chloride 
solution added to a solution of the acid, produces a 
blue-black colouration. When sulphuric acid is 
added to a concentrated solution of tannic acid, a 
white precipitate is formed, which in contact with 
air turns blue. 

Mandelic Acid, C 6 H 5 -CHOH-COOH, melts at 118, 



ORGANIC COMPOUNDS 45 

and is easily soluble in water. Oxidation with nitric 
acid produces benzaldehyde. The methyl ester 
melts at 52. 



B. HALOGEN SUBSTITUTED ACIDS. 

Monochloroacetie Acid, CH 2 C1-COOH, melting at 
62-63, heated with caustic potash forms glycollic 
acid. 

Dichloroacetic Acid, CHC1 2 'COOH, is a liquid, boiling 
at 189-191. 

Trichloroaeetie Acid, CC1 3 -COOH, melts at 55. 
When digested with caustic potash, chloroform and 
potassium carbonate are formed. 

Monobromoacetic Acid, CH 2 Br-COOH, melts at 
49-50. 

Dibromoaeetie Acid, CHBr 2 -COOH melts at 48. 

Tribromoacetie Acid, CBr 3 -COOH melts at 135. 

o-Chlorobenzoic Acid, C 6 H 4 , M.P. 137. 



Reduction with sodium amalgam produces benzoic 
acid. 

ra-Chlorobenzoie Acid, M.P. 153. 

p-Chlorobenzoie Acid, M.P. 236. 

o-Bromobenzoie Acid, C 6 H 4 <^ M.P. 147. 

ra-Bromobenzoic Acid, M.P. 155. 

p-Bromobenzoie Acid, M.P. 251. 

When the halogen benzoic acids are distilled with 
lime, the corresponding halogen derivatives of 
benzene are produced, 






46 THE IDENTIFICATION OF 

C. NITRO ACIDS. 

ivro 
o-Nitrobenzoie Acid, C 6 H ^QQQ H > M - 

m-Nitrobenzoic Acid, M.P. 141. 
p-Nitrobenzoic Acid, M.P. 238. 

These acids can be reduced to the corresponding 
amino-acids by tin and hydochloric acid. 

o-Nitrocinnamic Acid, C fl 



: CH . COOHj 
M.P. 237-240. 

m-Nitroeinnamie Acid, light yellow needles. M.P. 
197. 

p-Nitrocinnamic Acid, M.P. 286. 

Oxidation with alkaline potassium permanganate 
solution converts these acids into the corresponding 
nitrobenzaldehyde and nitrobenzoic acid. 

D. AMINO ACIDS. 

Aminoacetic Acid (glycine), CH 2 NH 2 -COOH, M.P. 
232, with decomposition, is converted by nitrous 
acid into glycollic acid. Ferric chloride added to a 
solution of glycine causes an intense red colouration 
which is discharged by acids, and restored by 
ammonia. 

Methyl Glycine (sarcosine), CH 2 NH(CH 3 )-COOH, 
M.P. 210-215, gives by the action of nitrous acid a 
nitroso-compound. When heated with soda-lime, 
sarcosine produces methylamine. 

Aceturic Acid (Acetoglycine), 

CH 2 NH-(COCH 3 )-COOH, 






ORGANIC COMPOUNDS 47 

melts at 206. On boiling with acids, it is decom- 
posed into glycine and acetic acid. 
Hippurie Acid (Benzoylglycine), 

CH 2 NH(COC 6 H 5 )COOH, 

melting at 187, is decomposed by boiling with 
dilute acids into benzoic acid and glycine. 

CH 2 NH-(COC 6 H 5 )-COOH +H 2 = C 6 H 5 -COOH + 
CH 2 NH 2 COOH. 

Aminopropionie Acid (Alanine) CH 3 -CHNH 2 -COOH. 
When heated with concentrated phosphoric acid 
solution it is decomposed into carbon dioxide, 
ammonia and acet aldehyde. 

Aspartic Acid, COOH -CH 2 -CHNH 2 -COOH. Nitrous 
acid converts it into malic acid. 

Asparagine, CONH 2 -CH 2 -CHNH 2 .COOH, forming 
large rhombic crystals, decomposes over 200 with- 
out melting. When heated with alkalies, ammonia 
and aspartic acid are produced. With nitrous acid 
it gives malic acid. 

o-Aminobenzoic Acid (Anthranilic Acid), 

C 6 H 4 <^ ^ melting at 144, when rapidly 

heated, decomposes into carbon dioxide and aniline. 
Nitrous acid transforms it into salicylic acid. 

Acetylanthranilic Acid, C 6 H 4 < CH3 , M.P.185 . 



Benzoylanthranilic Acid, C 6 H 4 < 65 , M.P. 

177. 

m-Aminobenzoie Acid forms small reddish crystals, 
M,P, 173-174, 



48 THE IDENTIFICATION OF 

p-Aminobenzoic Acid, M.P. 186-187. 
o-Aminocinnamic Acid, C 8 



CH . COOH 

M.P. 158-159, forms yellow needles and gives 
fluorescent solutions in ether and alcohol. 



XI. AROMATIC SULPHONIC 
ACIDS. 

THESE are, as a rule, very soluble in water and crystal- 
lize with difficulty. To identify them, it is best to 
prepare the sulphonamide and take its melting point. 
The sodium salts are easily obtained by salting out. 

PREPARATION OF THE AMIDE. One gram of the 
sodium salt and 2 grams phosphorus pentachloride 
are heated on a water bath. After the reaction is 
finished, the mixture is poured into water and the 
oily acid chloride extracted by means of ether. One 
gram of the oil and 2 grams of ammonium carbon- 
ate are heated on a water bath until the smell of the 
chloride disappears. The reaction product is then 
poured into water. After filtering, the amide is 
recrystallized from water and its melting-point 
determined. 

When a sulphonic acid or a salt is fused with alkali, 
a^henol is produced 
C fi H 5 -S0 3 Na +2NaOH = C 6 H 5 OH+Na 2 S0 3 +H 2 0. 

METHOD. One gram of the acid or salt is mixed 



ORGANIC COMPOUNDS 49 

with 2 grams solid caustic potash and heated in a 
nickel crucible to about 200 for one hour. After 
cooling the product is dissolved in water, the solu- 
tion acidified and the phenol extracted with ether 
and identified. 

By passing superheated steam into the sulphonic 
acid, a hydrocarbon results. 

Benzene sulphonic acid, C 6 H 5 S0 3 H, M.P. 50. 
M.P. of amide, 150. 

o-Toluene sulphonic acid, C 6 H 4 <^ 3 H '2H 2 0, 
deliquescent leaflets. M.P. of amide, 155. 

m-Toluene sulphonic acid, C 6 H 4 <^ O 3 H -H 2 0, 
deliquescent needles. M.P. of amide, 107. 

p-Toluene Sulphonic acid, C 6 H 4 3 -4H 2 0, 



crystallizes in leaflets. M.P. 92. M.P. of amide, 
137. 



o-Benzene disulphonic acid, CeH^ 3 , M.P. of 

chloride, 105 ; of amide, 233. 

m-Benzene disulphonic acid, M.P. of chloride, 53 ; 
of amide, 228. 

^-Benzene disulphonic acid, M.P. of chloride, 131 ; 
of amide, 288. 

o-Phenolsulphonic acid, CeH^^^-fHaO, melts 



above 50. When the potassium salt is treated 
with benzoyl chloride, potassium chloride is preci- 
pitated, and on extraction with ether, phenyl 
benzoate is obtained, 



50 THE IDENTIFICATION OF 



w-Phenolsulphonic acid, CoH. i ^^ r r -2H20,crystal- 

^bUsii 

lizes in fine needles. Ferric chloride produces in 
solutions of the acid, a violet colouration. 

2>Phenolsulphonic Acid is oxidized by manganese 
dioxide and sulphuric acid to quinone. When 
boiled with hydriodic acid, >-phenolsulphonic acid 
is decomposed into phenol and sulphuric acid. 

Cl 
o-Chlorobenzenesulphonic acid, C 6 H 4 <^~ JT, The 

chloride melts at 28-5 ; the amide at 188. 

m-Chlorobenzenesulphonie acid. The chloride is an 
oil ; the amide melts at 148. 

p-Chlorobenzenesulphonic acid. M.P. of chloride, 
53 ; of amide, 143. 

o-Bromobenzenesulphonic acid, C 6 H 4 <^^ ^. M.P. 

of chloride, 51 ; of amide, 186. 

m-Bromobenzenesulphonie acid. The chloride is 
oily. M.P. of amide, 154. 

p-Bromobenzenesulphonic acid, melts at 88. M.P. 
of chloride, 75 ; of amide, 166. 

o-Iodobenzenesulphonie acid, C 6 H 4 <^gQ g. M.P. 

of chloride, 51 ; of amide, 170. 

p-Iodobenzenesulphonie acid. The chloride melts 
at 86-87; the amide at 183. 

o-Nitrobenzenesulphonic Acid, c sH 4 <;^ 2 H . M.P. 

of chloride, 67 ; of amide, 186. 

m-Nitrobenzenesulphonic acid. M.P. of chloride, 
60-5 j of amide, 161. 



ORGANIC COMPOUNDS 51 

p-Nitrobenzenesulphonic acid. The chloride is oily ; 
the amide melts at 181. 
p-Aminobenzenesulphonic acid (Sulphanilic acid), 

C 6 H 4 <^^ \r, when oxidized gives quinone. Fusion 

with caustic potash produces aniline and not amino- 
phenol. 

SO TT 
o-Sulphobenzoie acid, <^*<C?n> when ann y- 



drous melts at 250. On fusion with caustic potash 
it is converted into salicylic acid. The imino deriva- 

SO 
tive, C 6 H 4 <^i^' 2 ^>NH, known as Saccharin, melts 

with partial decomposition at 220. By heating with 
alkalies, saccharin is decomposed into ammonia and 
o-sulphobenzoic acid. The sodium salt, 

a (the saccharin of commerce) is 



readily soluble in water. 

a-Naphthalene sulphonic acid, C 10 H 7 S0 3 H-H 2 0, 
M.P. 85-90. The chloride crystallizes from ether 
in leaflets, melting at 66. The amide melts at 150. 
Potassium permanganate in acid solution oxidizes 
the sulphonic acid to phthalic acid. 

/3-Naphthalene sulphonic acid, M.P. 161. The 
chloride melts at 76 ; the amide at 212. 



52 THE IDENTIFICATION OF 

XII. ACID ANHYDRIDES. 

THE aliphatic acid anhydrides are mostly colourless 
liquids, insoluble in water, readily soluble in alcohol 
and ether, with boiling points higher than those of 
the corresponding acids. The aromatic acid anhy- 
drides are solids with melting-points lower than those 
of the corresponding acids. Water slowly hydro- 
lyses anhydrides with formation of acids. With 
alkalies they readily form salts of the corresponding 
acids, and with alcohols, esters are produced. 

Acetic anhydride, (CH 3 CO) 2 0, B.P. 137-138. 
CH 2 CO V 

Succinic Anhydride, | X), M.P. 119-120, 

CH 2 CO 
reverts to the acid in moist air. 

Benzoic anhydride, (C 6 H 5 CO) 2 0, M.P. 42. 

PO 
Phthalie anhydride, C 6 H 4 <^>0, melts at 128 

and sublimes readily in long needles. When fused 
with resorcinol, fluorescein is produced (see p. 26). 

= 2H2 




>0 
C 6 H 3 OH 



ORGANIC COMPOUNDS 53 

XIII. ACID HALIDES. 

THESE are pungent-smelling liquids, readily con- 
verted by water into the acid, or by alkali into the 
salt of the acid. 

Acetyl chloride, CH 3 -COC1, B.P. 55. 

Acetyl bromide, B.P. 81. 

Acetyl iodide, B.P. 108. 

Propionyl chloride, C 2 H 5 -COC1, B.P. 80. 

Propionyl bromide, B.P. 104. 

Propionyl iodide, B.P. 127-128. 

Malonyl chloride, 

CH 2 -COC1 
Succinyl chloride, | , B.P. 190-192. 

CH 2 -COC1 

Benzoyl chloride, C 6 H 5 -COC1, B.P. 198. 
Benzoyl bromide, B.P. 218-219. 

Phthalyl chloride, C 6 H 4 , B.P. 275. 



XIV. ACID AMIDES. 

THESE are well crystallized substances with definite 
melting points. They are, as a general rule, less 
soluble in water than the ammonium salts of the cor- 
responding acids. When heated with alkalies, they 
give ammonia and the salt of the acid. With 



54 THE IDENTIFICATION OF 

nitrous acid they yield nitrogen and the correspond- 
ing acid. 

Acetamide, CH 3 -CONH 2 , M.P. 82-83. 

Propionamide, C 2 H 5 -CONH 2 , M.P. 79. 

Acetobromamide, CH 3 -CONHBr + H 2 0, M.P. 70- 
80, when boiled with caustic potash gives potassium 
bromide, carbon dioxide and methylamine. The 
anhydrous compound melts at 108. 
CONH 2 

Oxamide, | , sublimes on heating. It is 

CONH 2 

insoluble in water and in alcohol. 

CONH 2 

Oxamic acid, , M.P. 210 with decompo- 

COOH 

sition. 

CONH 2 
Oxamethane, , M.P. 114-115, when 

COOC 2 H 5 

boiled with caustic potash yields ammonia, ethyl 
alcohol and potassium oxalate. 

CH 2 -CONH 2 
Succinamide, | ,at 200 is converted into 

CH 2 -CONH 2 
the imide and ammonia. 

Cyanamide, CN-NH 2 , M.P. 40, with copper sul- 
phate gives a black compound, copper cyanamide, 
CNaCu. 1 

Benzamide, C 6 H 5 -CONH 2 , M.P. 128, is soluble in 
hot water, alcohol and ether. 

1 Calcium cyanamide CN 2 Ca is a commercial product. 
On addition of water, ammonia is evolved. 



ORGANIC COMPOUNDS 55 



Phthalic Diamide, C 6 H 4 < 2 , on heating 

^UUJN1 2 

changes to phthalimide with loss of ammonia. 



XV. ACID IMIDES. 

THE imides, like the acid amides, are hydrolysed by 
boiling with alkalies. The only common imides are 
the following : 

CH 2 CO V 
Succinimide, | >>NH, M.P. 126. 

CH 2 CO / 

Phthalimide, C 6 H 4 <^>NH, M.P. 233-234. 

Alcoholic caustic potash precipitates the potassium 

CO 
salt, C 6 H 4 <^p^^>NK, from a solution of phthalimide 

in alcohol. This salt is insoluble in alcohol and ether, 
and sparingly soluble in water. 



XVI. ACID ANTLIDES. 

THESE are hydrolysed by heating with concentrated 
hydrochloric acid or alkali and the aniline distilled 
with steam from an alkaline solution. The acid is 
then identified in the non-volatile residue. 

Formanilide, H-CONHC 6 H 5 , melting at 46, is 



56 THE IDENTIFICATION OF 

readily soluble in water, alcohol and ether. With 
concentrated caustic soda V)lution there is produced 
a crystalline sodium compound, H-CONNaC 6 H 5 . 
Aeetanilide (antifebrin) CH 3 -CONHC 6 H 5 , M.P.lirH 

COOH 

Oxanilic acid, | *H 2 0, M.P. (anhydrous) 

CONHC 6 H 5 

149-150. 

CONHC 6 H 5 

Oxanilide, , M.P. 245. 

CONHC 6 H 5 

Benzanilide, C 6 H 5 -CONHC 6 H 5 , M.P. 161-162. 



XVII. ESTERS. 

THESE are mostly pleasant-smelling, volatile liquids, 
insoluble in water. . (Methyl oxalate and methyl 
tartrate are solids.) 

A small quantity of the ester is hydrolysed with 
10 per cent, alkali solution, under a reflux condenser. 
Two-thirds of the liquid are distilled over, de- 
hydrated with potassium carbonate and examined 
for the alcohol. The residue in the distilling flask 
contains the alkali salt of the acid. 
Formates -methyl, B.P. 32-5. 

-ethyl, B.P. 54-5. 

-propyl, B.P. 82-83. 

-butyl, B.P. 107. 

-rc-amyl, B.P. 130-5. 



ORGANIC COMPOUNDS 57 

Acetates -methyl, B.P. 57-5. 

-ethyl, B.P. 77. 

-propyl, B.P. 101. 

-butyl, B.P. 125. 

-isobutyl, B.P. 116. 

-w-amyl, B.P. 148. 
Glycol monoacetate, B.P. 182. 
Glycol diacetate, B.P. 186-187. 
Glycerol triacetate, B.P. 258-259. 
Propionates-methyl, B.P. 79-5. 

-ethyl, B.P. 99. 
Butyrates-methyl, B.P. 102-3. 

-ethyl, B.P. 120. 
Oxalates-dimethyl, M.P. 54. 
-diethyl, B.P. 186. 
Malonates-dimethyl, B.P. 181-182. 

-diethyl, B.P. 198. 
Succinates-dimethyl, M.P. 18, B.P. 195. 

-ethyl, B.P. 216. 
Malates-dimethyl, B.P. 122 at 12 mm. 

-diethyl, B.P. 129 at 12 mm. 

-rc-dipropyl, B.P. 150 at 12 mm. 

Ethereal malates on heating under ordinary pres- 
sure decompose into the corresponding fumarates. 

Tartrates -dimethyl, M.P. 48. 

-diethyl, B.P. 280. 

-rc-dipropyl, B.P. 303. 
Benzoates -methyl, B.P. 199. 

-ethyl, B.P. 213. 

-n-propyl, B.P. 229. 



58 THE IDENTIFICATION OF 

Glyeol di-benzoate, M.P. 73. 
Glyeerol tri-benzoate, M.P. 76. 
Salicylates -methyl, B.P. 224. 

-ethyl, B.P. 231-5. When distilled 
with barium oxide ethyl phenyl 
ether is produced, 
-phenyl (salol), M.P. 42-43. 
Phthalates -dimethyl, B.P. 282. 
-diethyl, B.P. 288. 
-diphenyl, M.P. 70. 

Cinnamates -methyl, M.P. 36, B.P. 260. 
-ethyl, B.P. 271. 

phenyl, M.P. 72. On distillation in 
air, carbon dioxide and stilbene 
are formed. 



XVIII. QUINONES. 

THESE compounds are characterized by their colour 
(yellow or red), peculiar odour and volatility in 
steam. With the exception of anthraquinone and 
phenanthr a quinone, they are readily reduced by 
sulphur dioxide to the corresponding dihydric 
phenols. 

Benzoquinone (quinone), C 6 H 4 2 , M.P. 116, is solu- 
ble in water. With phenol, quinone forms pheno- 
quinone, C 6 H 4 02-2C6H 5 OH, crystallizing in red 
needles, melting at 71. Phenoquinone is turned 



ORGANIC COMPOUNDS 59 

blue by caustic potash, green by barium hydroxide. 
Quinone liberates iodine from potassium iodide. 

o-Quinone forms bright red crystals. It has no 
smell and is not volatile. It is reduced by sul- 
phurous acid to catechol. 

a-Naphthoquinone, C 10 H 6 2 , M.P. 125, is yellow and 
on oxidation with nitric acid, forms phthalic acid. 

/3-Naphthoquinone decomposes about 120. It 
crystallizes in red needles. It is odourless and non- 
volatile. 

Anthraquinone, C 14 H 8 2 , M.P. 273, when treated 
with zinc dust and caustic soda, produces oxanthranol, 

C 6 H 4 < C H >C 6 H 4 , which is red. The latter 

compound is easily oxidized on standing in air, 
anthraquinone being again formed. 

Phenanthraquinone, M.P. 205, is not reduced by 
sulphur dioxide. It dissolves in concentrated sul- 
phuric acid to a dark green solution. When ignited 
with zinc dust, phenanthraquinone gives phenan- 
threne. The monoxime C 14 H 8 0:NOH melts at 
158. 

Chloranil (tetrachlorquinone), C 6 C1 4 2 , forms 
golden-yellow leaflets, with a smell reminiscent of 
Harris tweed. It sublimes undecomposed. With 
caustic potash it forms the purple potassium chlor- 
anilate, C 6 C1 2 (OK) 2 02. By the addition of acid to 
the latter, chloranilic acid, which crystallizes in 
reddish scales, is liberated. 



60 THE IDENTIFICATION OF 



XIX. CARBOHYDRATES. 

THESE are solids, which, with the exception of starch, 
are soluble in water. 

d-Glucose (dextrose), C 6 H 12 6 ,H 2 0, M.P. 86. 
The anhydrous compound melts at 145. Glucose 
reduces Fehling's solution. Glucosazone melts at 
204-205. Glucose pentabenzoate melts at 179. 

PREPARATION OF THE OSAZONE. One gram of 
the sugar is dissolved in 5 cc. water, and 4 grams 
phenylhydrazine in 5 grams glacial acetic acid are 
added. The solution is heated on a water-bath for 
about ten minutes, when the osazone separates in 
yellow crystals. These are dried and the melting- 
point determined. This should be done quickly 
as the osazone decomposes to some extent in the 
neighbourhood of the melting-point. 

Galactose, M.P. 163-164. The osazone melts at 
193-194. 

Fructose (laevulose), M.P. 95. With phenyl- 
hydrazine it gives c-glucosazone. The pentaben- 
zoate melts at 78-79. 

Cane Sugar, Ci 2 H 22 On, melting at 160, does not 
reduce Fehling's solution. When boiled with dilute 
acids, glucose and fructose are produced. It forms 
no osazone. With benzoyl chloride it gives a hexa- 
benzoate, melting at 109. 

Lactose (Milk sugar), Ci 2 H2 2 Oii,H 2 0, becomes 
anhydrous at 140, and melts with decomposition 



OKGANIC COMPOUNDS 61 

at 205. The osazone melts at 200. Lactose 
reduces Fehling's solution. 

Maltose, C^H^Oi^HaO, loses water at 100. 
When boiled with dilute acids, glucose is formed. 
The osazone melts at 190-191. 

Starch (C 6 H 10 5 ) n > with iodine gives a blue colour, 
which disappears on heating. Starch is hydrolysed 
by heating with dilute acids, forming glucose. On 
boiling with water starch swells up and partially 
dissolves. 



XX. GLUCOSIDES. 

THESE, on hydrolysis with dilute acids or alkalies, 
give a sugar generally glucose and other sub- 
stances. 

Myronie Acid, C 1 oHi 9 OioNS 2 , usually occurs as the 
potassium salt. When boiled with barium hy- 
droxide it is decomposed into glucose, allyl isothio- 
cyanate (see p. 92) and potassium hydrogen 
sulphate. 

Arbutin, C 6 H 4 <^ Hll 5 |J) is soluble in water. 

When ferric chloride is added to the aqueous solu- 
tion, the latter is turned deep blue. On hydrolysis 
with dilute sulphuric acid, glucose and hydroquin- 
one are produced. 

Salicin, C 6 H<OC 6 H^0 5 W, melting at 201, on 



62 THE IDENTIFICATION OF 

hydrolysis gives glucose and saligenin. Con- 
centrated sulphuric acid produces a deep red 
colour. It is oxidized by chromic acid mixture to 
carbon dioxide, formic acid and salicyl aldehyde. 

Amygdalin, CaoH^OnN^HaO, loses water at 120, 
melting at 200 and is hydrolysed by dilute acids 
into glucose, benzaldehyde and hydrocyanic acid. 

Helicin, C 6 H 4 <^ 6 ^ ll0s , fH 2 0, loses water at 

100 and melts at 175. On hydrolysis with dilute 
acids it gives glucose and salicyl aldehyde. 



XXL AMINES. 

ALIPHATIC AMINES. 

THE lower members are inflammable gases possessing 
an ammoniacal odour and are readily soluble in 
water, while the higher members are liquids. With 
acids they form salts which are soluble in water and 
in alcohol. 

Nitrous Acid converts primary amines into the cor- 
responding alcohols, with evolution of nitrogen 

E-NH 2 + HONO = R-OH + N 2 + H 2 0. 

Secondary amines are converted into yellow 
nitrosoamines 

R 2 NH + HONO = R 2 N-NO + H 2 0. 
Tertiary amines are unacted upon. 



ORGANIC COMPOUNDS 63 

METHOD. A small quantity of the amine is dis- 
solved in dilute hydrochloric acid, care being taken 
that an excess of acid is present. To the cooled 
solution, a solution of sodium nitrite is added until 
free nitrous acid is present (starch iodine test). 

Primary amines are also distinguished by giving 
the carbylamine test with chloroform and alcoholic 
potash 
R-NH 2 + CHC1 3 + 3KOH = R-NC + 3KC1 + 3H 2 0. 

METHOD. About 0-1 gram of the amine is mixed 
with 3 drops chloroform and about 2 cc. alcoholic 
potash solution, and gently heated. A disgusting 
smell of carbylamine is evolved. 

N.B. The lower aliphatic amines are usually 
met with as salts. 

Methylamine Hydroehloride, CH 3 NH 2 -HC1, forms 
deliquescent crystals. 

Ethylamine, C 2 H 5 NH 2 , B.P. 18-19. The hydro- 
chloride melts at 76-80. 

Diethylamine, (C 2 H 5 ) 2 NH, B.P. 56. M.P. of hydro- 
chloride 215-217. 

Triethylamine, (C 2 H 5 ) 3 N, B.P. 89. 

Propylamine, (C 3 H 7 )NH 2 , B.P. 49. The 
chloride melts at 157-158. 

Isopropylamine, (CH 3 ) 2 CHNH 2 , B.P. 31-32. The 
hydrochloride is deliquescent. 

7i-Butylamine, C 4 H 9 NH 2 , B.P. 76. 

rc-Amylamine, CgHnNKU B.P. 103. 

Allylamine, CH 2 : CH-CH 2 NH 2 . B.P. 56. 

Ethylenediamine, C 2 H 4 (NH 2 ) 2 , B.P. 116. Nitrous 
acid converts it into ethylene oxide. 



64 THE IDENTIFICATION OF 

Tetramethylenediamine (putrescine), C 4 H 8 (NH 2 ) 2 , 
M.P. 27-28. 

Pentamethylene Diamine (cadaverine), C 5 H 10 (NH2)2. 
B.P. 178-179. 

AROMATIC AMINES. 

These are liquids or solids, and behave in many 
respects like the aliphatic amines. The primary 
compounds give the carbylamine reaction. 

ACTION OF NITKOUS ACID. If the amino group is 
in the nucleus there are formed in cold acid solution 
diazonium salts, which on heating evolve nitrogen 
and produce phenols. If to a solution of a diazonium 
salt /9-naphthol in caustic soda is added, a coloured 
precipitate of an azo-compound appears. 

PREPARATION OF A DIAZONIUM SALT. The amine 
is dissolved in a large excess of dilute hydrochloric 
acid and cooled in ice-water. Sodium nitrite solu- 
tion is added in small quantities at a time, the mix- 
ture being well shaken after each addition, until, 
after standing for a few minutes, free nitrous acid 
can be detected by starch-iodide paper. 

If the amino group is in the side chain, no diazon- 
ium salt is formed, and the amine behaves like the 
aliphatic compounds. 

With secondary aromatic amines, nitroso-deriva- 
tives are formed, as in the case of aliphatic com- 
pounds. 

Dialkylanilines with nitrous acid form para- 
nitroso compounds, the free bases of which are 
usually green, while the hydrochlorides are orange- 
coloured. 



ORGANIC COMPOUNDS 65 

To completely identify an aromatic amine, its 
acetyl compound is prepared and its melting-point 
determined. 

METHOD. To 1 gram of the amine is added 1 gram 
acetic anhydride. The solid acetyl compound 
usually separates immediately. It is recrystallized 
from water or alcohol and its melting-point taken. 

Aniline, C 6 H 5 NH 2 , B.P. 182-183. A chip of 
pine wood dipped first in hydrochloric acid and then 
in aniline, is turned yellow. Bleaching powder 
solution, when shaken with aniline becomes violet. 
On diazotizing and warming, aniline is converted 
into phenol. Acetanilide melts at 112. 

Methylaniline, C 6 H 5 NHCH 3 , B.P. 193-194, forms 
a nitroso-derivative, C 6 H 5 NCH 3 -NO, M.P. 12-15. 
The acetyl derivative melts at 101-102. 

Dimethylaniline, C 6 H 5 N(CH 3 ) 2 , boils at 195. The 
para-nitroso compound, which can be separated from 
its salts by means of sodium carbonate and extrac- 
tion with ether, forms green crystals of metallic 
appearance, melting at 85. 

Ethylaniline, C 6 H 5 NHC 2 H 6 , B.P. 206. The acetyl 
derivative melts at 54*5. 

Diethylaniline, C 6 H 5 N(C 2 H 6 ) 2 , B.P. 213-214. 
p-Nitroso-compound M.P. 84. 

Diphenylamine, (C 6 H 5 ) 2 NH, melts at 54 and has a 
pleasant odour. The nitroso-derivative melts at 
66-5. 

Triphenylamine, (C 6 H 5 ) 3 N, M.P. 127. With con- 
centrated sulphuric acid, there is produced a violet 
colouration, which changes to green. 



66 THE IDENTIFICATION OF 

pro 

o-Toluidine, C 6 H 4 <^ 3 , boils at 197. Ferric 

chloride precipitates a blue compound from its solu- 
tion in hydrochloric acid. The acetyl compound 
melts at 110. 

ra-Toluidine, B.P. 202. The acetyl compound 
melts at 65. 

p-Toluidine, M.P. 45. The melting point of the 
acetyl compound is 153. 

a-Naphthylamine, C 10 H 7 NH 2 , M.P. 50. On oxida- 
tion with chromic acid, a-naphthaquinone is pro- 
duced. 

/3-Naphthylamine, M.P. 111-112. Potassium per- 
manganate oxidizes it to phthalic acid. 

Benzylamine, C 6 H 5 -CH 2 NH 2 , B.P. 183-185 is 
strongly alkaline. 

o-Phenylenediamine,C 6 H 4 <^ 2 ,M.P. 102. When 

ferric chloride is added to the hydrochloric acid 
solution, a dark red colouration is produced, and 
there quickly separate red needles of diamido- 

phenazine C 6 H 4 <^>C 6 H 2 (NH 2 ) 2 . The di-acetyl 

compound of o-phenylenediamine melts at 185-186. 
m-Phenylenediamine, M.P. 63. Dilute nitrous acid 
produces a brown colouration owing to the formation 
NH 2 

M" ,NH 2 
i i 
N N I 

NH 3 



OEGANIC COMPOUNDS 67 

p-Phenylenediamine, M.P. 147. When about 0-1 
gram is dissolved in dilute hydrochloric acid and a 
little sulphuretted hydrogen water added along with 
a few drops of ferric chloride solution, and the mix- 
ture warmed, there appears a deep violet colouration 
(the so-called Lauth violet), 

HN = / \ =N - 



Benzidine, NH 2 C 6 H 4 -C 6 H 4 NH 2 melting at 122, 
forms silvery leaflets, easily soluble in hot water and 
alcohol. The sulphate is insoluble in water. 



HALOGEN AMINES. 

pi 
o-Chloroaniline, C 6 H 4 <^ H , B.P. 207. The 

acetyl compound melts at 87-88. 

m-Chloroaniline, B.P. 230. M.P. of acetyl com- 
pound, 72-5. 

p-Chloroaniline, M.P. 70. M.P. of acetyl com- 
pound, 172-5. 

o-Bromoaniline, GsH 4 <^g , M.P. 31. M.P. of 

acetyl compound, 99. 

ra-Bromoaniline, M.P. 18, B.P. 251. M.P. of 
acetyl compound, 87' 5. 

23-Bromoaniline, M.P. 63. M.P. of acetyl com- 
pound, 167-168. 



68 THE IDENTIFICATION OF 

Cl 
Sym. Trichloroaniline, NH 2 / \ Cl, M.P. 

Cl 
77-5. M.P. of acetyl compound, 204. 

Sym. Tribromoaniline, M.P. 119-120. M.P. of 
acetyl compound, 232. 



XXII. NITRO-COMPOUNDS. 

ALIPHATIC NITRO-COMPOUNDS. 

THESE are agreeably-smelling liquids, soluble in 
water. Many of them dissolve in alkalies. 

ACTION OF NITROUS ACID. With a primary ali- 
phatic nitro-compound nitrous acid produces a red 
colouration due to the formation of a nitrolic acid. 



K-CH 2 N0 2 + HONO= R-C< +H 2 0. 

The potassium salt is red. 

With a secondary compound there is produced a 
dark blue colouration, a pseudo-nitrol being formed 
R 2 CHN0 2 + HONO = !^C< 2 + H 2 0. 



Tertiary compounds are unacted upon by nitrous 
acid. 

METHOD. A small quantity of the compound is 
shaken in a test-tube with sufficient caustic soda to 
form a clear solution. A few drops of a solution of 
sodium nitrite are added and finally dilute sulphuric 



ORGANIC COMPOUNDS 69 

acid drop by drop. In the case of a primary com- 
pound excess of acid destroys the red colouration, 
which, however, is restored by addition of caustic 
soda. 

REDUCTION. Nitro-compounds are readily re- 
duced to amines. 

METHOD. A few pieces of granulated zinc are 
placed on a test-tube and covered with caustic potash 
solution. Two cc. of the nitro-compound are intro- 
duced and the mixture warmed. The amine will 
be observed by its smell and its action on red litmus 
paper. 

Nitromethane, CH 3 N0 2 , B.P. 101. Alcoholic 
caustic soda precipitates the sodium compound, 
CH 2 :NO 2 Na. Concentrated hydrochloric acid de- 
composes it with formation of formic acid. 

Nitroethane, C 2 H 5 N0 2 , B.P. 114-115. Concen- 
trated hydrochloric acid converts it into acetic acid. 

Nitropropane, C 3 H 7 N0 2 , B.P. 130-131. 

Tertiary Nitrobutane, (CH 3 ) 3 -CN0 2 , is crystalline, 
melting at 24. It is insoluble in alkalies. 

AROMATIC NITRO-COMPOUNDS. 

These are generally yellow oils or solids, insoluble 
in water, dilute hydrochloric acid or dilute caustic 
soda solution. Di-nitro and tri-nitro compounds 
impart a deep yellow colour to caustic soda solution . 

They are reduced to amines by acid reducing 
agents. 

METHOD. A small quantity of the nitro-compound 






70 THE IDENTIFICATION OF 

is treated with zinc dust and hydrochloric acid, heat 
being applied if necessary. The mixture is diluted 
and rendered alkaline with caustic soda. It is then 
extracted with ether and the amine identified. 

Nitrobenzene, C 6 H 5 N0 2 , B.P. 209, is a yellow oil 
with an odour of bitter almonds. On reduction it 
yields aniline. 

o-Nitrotoluene, C 6 H 4 <^ 3 , boils at 218. It gives 

o-toluidine on reduction. 

ra-Nitrotoluene, melts at 16, and boils at 230-231. 
p-Nitrotoluene, M.P. 54. 

o-Dinitrobenzene, C 6 H 4 <^ 2 , M.P. 117-118. On 

reduction it gives o-phenylenediamine. 

m-Dinitrobenzene, M.P. 91. 

p-Dinitrobenzene, M.P. 171-172. 

a-Nitronaphthalene, Ci H 7 N0 2 , melting at 61, on 
reduction yields a-naphthylamine and with chromic 
acid is oxidized to nitrophthalic acid. 

/3-Nitronaphthalene, M.P. 79, gives on reduction 
/3-naphthylamine . 



NITROPHENOLS. 

These compounds, on reduction with tin and 
hydrochloric acid, yield aminophenols. 

o-Nitrophenol, C 6 H 4 <^ 2 , melting at 44, has an 
intense yellow colour and a peculiar odour. It is 



OKGANIC COMPOUNDS 71 

easily volatile in steam. The sodium salt gives a 
red solution in water. 

ra-Nitrophenol, M.P. 96, forms sulphur-yellow 
crystals. 

p-Nitrophenol, M.P. 114, forms colourless needles 
which turn pink on exposure to air. The potassium 
salt is yellow. Phosphorus pentachloride converts 
the phenol into p-chloronitrobenzene, M.P. 83. 
OH 

N 2 'M.P. 122-123 forms 

NO 2 

yellow leaflets soluble in hot water. With aromatic 
hydrocarbons crystalline molecular compounds are 
obtained (see Naphthalene, p. 17). When picric 
acid is warmed with a concentrated solution of potas- 
sium cyanide, a dark red solution of isopurpuric acid 
is produced. 

NITROKETONES. 

o-Nitroaeetophenone, C 6 H 4 N0 2 CO-CH3, is an oil with 
a peculiar smell. It is oxidized by potassium per- 
manganate to o-nitrobenzoic acid. 

m-Nitroacetophenone forms needles melting at 80- 
81. The oxime melts at 131. 

23-Nitroacetophenone, crystallizes in yellow prisms, 
melting at 80-81. 

NITROANILINES. 

These are solids, yellow or orange in colour. They 



72 THE IDENTIFICATION OF 

have basic properties and are soluble in acids. On 
reduction with tin and hydrochloric acid the 
corresponding diamines are produced. 

o-Nitroaniline,C 6 H 4 <^jj 2 , crystallizes in orange- 
yellow needles, melting at 71. When boiled 
with alkali it loses ammonia with production of 
o-nitrophenol. The acetyl derivative melts at 92. 

m-Nitroaniline, melting at 114, forms yellow 
needles and is not acted on by alkali. The acetyl 
compound melts at 150. 

p-Nitroaniline, M.P. 147, is decomposed by boiling 
alkali solution into ammonia and ^-nitrophenol. 
The acetyl compound melts at 207. 
NH 2 

Picramide, 2 , forms orange-red 

N0 2 

needles melting at 188. When heated with alkali, 
alkali picrate is formed, and ammonia is evolved. 



XXIII. NITROSO-COMPOUNDS. 

Nitrosobenzene, C 6 H 5 NO, M.P. 68, when fused or 
in solution has an intense greenish-blue colour. 

^-Nitrosoaniline, C 6 H 4 <^Tr > forms steel-blue 



ORGANIC COMPOUNDS 73 

needles, melting at 174. On boiling with caustic 
soda, it forms ammonia and p-nitrosophenol. 



p-Nitrosophenol, CH<, M.P. 126, is slightly 



soluble in water, giving a light green solution. It 
is reduced by tin and hydrochloric acid to p-amino- 
phenol. Concentrated nitric acid oxidizes it to 
>-nitrophenol. 



Methyl-p-nitrosoaniline, C<nrnt / forms 

^ 



large crystals with metallic lustre, M.P. 118. When 
boiled with caustic soda solution, it is decomposed 
into nitrosophenol and methylamine. 

6H <NHCH 3 + H2 = C 6 
p-Nitrosodimethylaniline, C 6 H 4 <^; TT x , forms 



green crystals, melting at 85. The hydrochloride is 
yellow and is soluble with difficulty in water. Dilute 
caustic soda solution on warming decomposes the 
base into ^-nitrosophenol and dimethylamine. It 
does not give Liebermann's nitroso reaction. 

a-Nitrosonaphthol (a-naphthoquinone oxime), 
Ci H 6 (OH)(NO) 1 : 4, forms needles melting with 
decomposition at 193-194. 

/3-Nitrosonaphthol (/3-naphthoquinone oxime), 
C 10 H 6 (OH)(NO) 1 : 2, crystallizes in yellowish-green 
needles, melting with decomposition at 152. It 
dissolves in concentrated sulphuric acid with an 
intense red colour. When a neutral solution of the 



74 THE IDENTIFICATION OF 

sodium salt of /3-nitroso-naphthol is added to a cobalt 
salt solution, a brown-red precipitate is formed. 



XXIV. NITRILES AND ISONI- 
TRILES. 

THE nitriles are liquids or solids of low melting-point, 
and have an agreeable odour. When boiled with 
strong mineral acids they are hydrolysed into the 
corresponding acids 

CH 3 -CN + 2H 2 = CHs'COOH + NH 3 
With nascent hydrogen they are reduced to amines. 
CHs-CN + 4H=CH 3 -CH 2 NH 2 . 

HYDROLYSIS OF NITRILES. Two cc. of the sub- 
stance are boiled for some time with about 20 cc. 
concentrated hydrochloric acid. The liquid is then 
rendered alkaline with caustic soda and heated. 

The residual liquid is tested for the fatty acid. 

REDUCTION OF NITRILES. One cc. of the sub- 
stance is treated with 10 cc. dilute hydrochloric acid 
and a little zinc dust. The solution is rendered 
alkaline with caustic soda, and the amine identified. 

Acetonitrile, CH 3 'CN. is a colourless liquid, boiling 
at 81-82. 

Benzonitrile, C 6 H 5 -CN, B.P. 191, is an oil with the 
odour of bitter almonds. 

Isonitriles or Carbylamines are not usually met with 
unless in testing for primary amines. They are 



ORGANIC COMPOUND ( , 75 

liquids possessing a disgusting odour. On hydro- 
lysis with acids they yield formic acid and an 
amine. 

R-N^C + 2H 2 0=R-NH 2 +H-COOH. 



XXV. ISOCYANATES. 

THESE are liquids, which, when digested with caustic 
potash yield primary amines and potassium carbon- 
ate, and with acids, a salt of a primary amine and 
carbon dioxide 

R-N:C:0 +H 2 =RN-H 2 +C0 2 . 

Methyl Isocyanate, B.P. 44. 
Ethyl Isocyanate, B.P. 60. 
Allyl Isocyanate, B.P. 82. 
Phenyl Isocyanate, B.P. 165-166. 



XXVI. UREAS AND UREIDES. 

WHEN ureas and alkyl ureas are digested with caustic 
soda solution sodium carbonate remains, while 
from the former ammonia is evolved, from the latter 
amines. In the case of ureides, ammonia or amines 
may be given off, and the residue consists of sodium 
carbonate and the sodium salt of the acid of the 
ureide. 



76 THE IDENTIFICATION OF 

CO^ 2 + 2NaOH = Na 2 C0 3 +2NH 3 . 
-\JN-ti2 

+ 2NaOH=Na 2 C0 3 +CH 3 .NH 2 +NH 3 



CO NH COONa 

| >CO + 4NaOH = Na 2 C0 3 + + 

CO NH COONa 

2NH 3 

Urea, CO NH2 , M.P. 132-133, is a colourless solid; 



When treated with nitrous acid it is decomposed 
into nitrogen and carbon dioxide 

CO(NH 2 ) 2 + 2HONO = C0 2 + 2N 2 + 3H 2 0. 
With a solution of sodium hypobromite it gives the 
same decomposition products 
CO(NH 2 ) 2 + 3NaBrO =C0 2 + 3NaBr+N 2 + 2H 2 0. 

BIURET REACTION. When urea is heated above its 
melting-point, ammonia is evolved and a residue of 
biuret remains 

2CO(NH 2 ) 2 = NH 3 + NH 2 -CO-NH-CO-NH 2 . 

When the biuret is dissolved in water and copper 
sulphate added and then caustic potash drop by 
drop, a violet colouration appears. 



Methylurea, CO , crystallizes in prisms, 



melting at 102. On heating for some time it decom- 
poses into ammonia, methylamine and the dimethyl 
ester of cyanuric acid, which melts at 222. 



ORGANIC COMPOUNDS 77 



Ethylurea, CO , melts at 92. It decom- 



poses on heating, into ammonia, ethylamine and 
the diethyl ester of cyanuric acid, M.P. 173. 

CO NH 

Parabanic Acid (Oxalylurea), | ^>CO, on 

CO NH 

heating with caustic potash solution gives potassium 
oxalate, potassium carbonate and ammonia. 



Barbituric Acid (Malonylurea ) , CO ^>CH 2 , on 



heating with caustic potash solution yields potassium 
malonate, potassium carbonate and ammonia. 



Alloxan(Mesoxalylurea),CO ^>CO, has an 



acid reaction. Ferrous sulphate gives a deep blue 
colour to the solution. When alloxan is boiled with 
dilute nitric acid, it is decomposed into parabanic 
acid and carbon dioxide. 



Guanidine, CNH, is a deliquescent strongly 



basic substance. The nitrate, M.P. 214, dissolves 
with difficulty in water. When boiled with alkalies, 
guanidine is decomposed giving ammonia and alkali 
carbonate. 



78 THE IDENTIFICATION OF 



XXVII. URIC ACID GROUP. 



NH -CO 
C- 



Uric Acid, CO C-NH 

NH 



| || CO, is insoluble in 

NH - C- 



alcohol, and practically insoluble in water. 

1. When the acid is heated with soda lime 
ammonia is evolved. 

2. MUREXIDE TEST. A small quantity of the acid 
is moistened with concentrated nitric acid, and the 
mixture evaporated to dryness in a porcelain basin 
on a water-bath. There remains a reddish residue, 
which on addition of dilute ammonia solution 
changes to purple red, while alkali produces a violet 
colouration. 

3. Fehling's solution is reduced by uric acid. 

4. If a little of the acid be dissolved in a drop of 
caustic soda solution and this placed on filter paper 
which has been moistened with a solution of silver 
nitrate, a dark brown spot of metallic silver is 
immediately produced. 

5. On dry distillation, uric acid decomposes 
without melting, giving off ammonia and hydro- 
cyanic acid, 



ORGANIC COMPOUNDS 79 

NH-CO 

Xanthine, CO C NH V is a colourless 

I II >CH 

NH -C N/^ 

powder, soluble with difficulty in water, but very 
easily soluble in alkalies. 

When a small quantity of xanthine is warmed with 
freshly-made chlorine water and a trace of nitric 
acid until evolution of gas ceases, the solution 
then carefully evaporated to dryness, and the solid 
exposed to ammonia gas, a rose-red colour is pro- 
duced. 

If xanthine be evaporated with nitric acid (Sp. 
Gr. 1 -4), the residue is yellow. On addition of caustic 
potash it becomes yellowish red, and on warming 
violet-red. 

CH 3 N - CO 

Caffeine, CO C - NCH 3 M.P. 226-229, 

I li \CH , 
CH 3 N - C-N/" 

is fairly soluble in water and in alcohol. 

When evaporated with concentrated nitric acid 
it gives the murexide test (see Uric Acid). 

When caffeine is evaporated with chlorine water, 
it leaves a purple red residue, which on strongly 
heating becomes yellow, but on addition of ammonia 
is changed to red. 



80 THE IDENTIFICATION OF 

XXVIII. HALOGEN COMPOUNDS. 

ALIPHATIC. 

THE alkyl halides are liquids which have a high 
specific gravity, and are practically insoluble in 
water. They are hydrolysed to the corresponding 
alcohols by warming with an excess of alkali 
solution. 

Ethyl bromide, C 2 H 5 Br, B.P. 39. 

Ti-Propyl bromide, C 3 H 7 Br, B.P. 71. 

Isopropyl bromide, CH 3 -CHBr.CH 3 , B.P. 59-60. 

Methyl iodide, B.P. 43. 

Ethyl iodide, B.P. 72. 

Propyl iodide, B.P. 102. 

Isopropyl iodide, B.P. 89-5. 

Allyl chloride, CH 2 : CH-CH 2 C1, B.P. 46, has a 
leek-like odour. 

Allyl bromide, B.P. 70-71. 

Allyl iodide, B.P. 102-103. 

Methylene iodide, CH 2 I 2 , boils at 180 with partial 
decomposition. 

Ethylene chloride, CH 2 C1-CH 2 C1, B.P. 84. 

Ethylene bromide, B.P. 131-132. 

Ethylene iodide, melts at 81-82. 

Chloroform, CHC1 3 , B.P. 61 -5, is a colourless 
non-inflammable liquid. When boiled with alco- 
holic caustic potash, potassium formate and potas- 
sium chloride are formed 

OHC1 3 + 4KOH = H-COOK + 3KC1 + 2H 3 0, 



ORGANIC COMPOUNDS 81 

The carbylamine test may also be applied (see 
page 11). 

Bromoform, CHBr 3 , B.P. 151. 

lodoform, CHI 3 , M.P. 119-120, crystallizes in 
brilliant yellow leaflets of a characteristic odour. 

Carbon tetrachloride, CC1 4 , B.P. 76-77, is a pleasant 
smelling liquid. When treated with zinc and 
hydrochloric acid, it is reduced to chloroform. 
On heating with alcoholic potash it is decomposed 
into potassium carbonate and potassium chloride. 

CC1 4 + 6KOH = K 2 C0 3 + 4KC1 + 3H 2 0. 

AROMATIC HALOGEN COMPOUNDS 

are divided into two classes : 

1. True aromatic halogen compounds, i.e. those 
with the halogen attached to the benzene nucleus. 

2. Those with the halogen in the side chain. 
The members of the first class are colourless 

liquids or solids, with a faint, agreeable odour. 
They are insoluble in water, but readily soluble 
in the other common solvents. They easily form 
nitro-derivatives. Caustic alkali does not readily 
remove the halogen from these compounds. 

Monochlorobenzene, C 6 H 5 C1, B.P. 132. 

o-Dichlorobenzene, C 6 H 4 C1 2 , B.P. 179. 

ra-Dichlorobenzene, B.P. 172. 

p-Diehlorobenzene, M.P. 53. 

Monobromobenzene, C 6 H 5 Br,$B.P. 156-157. 

o-Dibromobenzene, C 6 H 4 Br 2 , B.P. 224. 

w-Dibromobenzene, B.P. 219. 

G 



82 THE IDENTIFICATION OF 

p-Dibromobenzene, M.P. 89. 
lodobenzene, C 6 H 5 I, B.P. 188. 

o-Chlorotoluene, CeH^ 3 , B.P. 156. 

ra-Chlorotoluene, B.P. 150. 
p-Chlorotoluene, B.P. 163. 

o-Bromotoluene, C 6 H 4 <^ 3 , B.P. 181. 

ra-Bromotoluene, B.P. 183-184. 
p-Bromotoluene, M.P. 28-29. 
a-Chloronaphthalene, C 10 H 7 C1, B.P. 263. 
/3-Chloronaphthalene, M.P. 56, B.P. 265. 

The compounds with halogen in the side chain 
behave like aliphatic halogen compounds. 

Benzyl chloride, C 6 H 5 -CH 2 C1, B.P. 175, when 
boiled with a solution of copper nitrate, benzaldehyde 
is formed 

2C 6 H 5 -CH 2 C1 +Cu(N0 3 ) 2 = 2C 6 H 5 -CHO + CuCl 2 + 
2HN0 2 . 

Benzal chloride (benzylidene chloride ), C 6 H 5 -CHC1 2 , 
B.P. 206, forms benzaldehyde, when heated with 
milk of lime 

C 6 H 5 .CHCl 2 +Ca(OH) 2 =C 6 H 5 .CHO+CaCl 2 +H 2 0. 

Benzotrichloride, C 6 H 5 -CC1 3 , B.P. 2 13, on heating 
with milk of lime, gives calcium benzoate 

2C 6 H 5 .CC1 3 +4Ca(OH) 2 = (C 6 H 5 -COO) 2 Ca + 
3CaCl 2 + 4H 2 0. 



ORGANIC COMPOUNDS 83 



XXIX. AZO COMPOUNDS. 

THESE compounds are coloured solids, which on 
reduction produce amino compounds. 

C 6 H 5 N:NC 6 H 5 + 4H = C 6 H 5 NH 2 + C 6 H 5 NH 2 . 

azobenzene 



p-amidoazobenzene p-phenylenediamine 

C 6 H 5 N:NC 6 H 4 OH+4H = C 6 H 5 NH 2 +C 6 H 4 NH 2 OH 

p-oxyazobenzene p-aminophenol 

S0 3 HC 6 H 4 N : NC 6 H 4 N(CH 3 ) 2 + 4H = 

Helianthine 

S0 3 HC 6 H 4 NH 2 + NH 2 C 6 H 4 N(CH 3 ) 2 

Sulphanilic acid p-amido-dimethylaniline 

METHOD OF REDUCTION. About 3 grams of the 
compound are warmed with zinc dust and water 
until the colour has disappeared. The mixture is 
then extracted with ether and the ethereal solution 
evaporated to dryness. The residue may be : 

1. A mixture of two amines. 

2. A mixture of an amine and an aminophenol. 

3. A mixture of an amine and an aminosulphonic 
acid. 

MIXTURE OF Two AMINES. The residue of liquid 
is distilled and the first and last fractions treated 
with acetic anhydride. The acetyl compounds 
thus formed are then identified by their melting 
points. 

MIXTURE OF AN AMINE AND AN AMINOPHENOL. 
The aminophenol is extracted from the mixture with 
alkali. 



84 THE IDENTIFICATION OF 

MIXTURE OF AN AMINE AND AN AMINOSTJLPHONIC 
ACID. The mixture is neutralized with alkali, the 
amine extracted with ether, and identified. The 
aminosulphonic acid is liberated by adding hydro- 
chloric acid to the alkali salt. 

Azobenzene, C 6 H 5 N : NC 6 H 5 , M.P. 68, is easily 
soluble in alcohol. When treated with tin and 
hydrochloric acid, benzidine is produced. 

p-Aminoazobenzene, C 6 H 5 N : NC 6 H 4 NH 2 , forms 
yellow leaflets melting at 125-126. It is oxidized 
by sulphuric acid and manganese dioxide with 
formation of quinone. The hydrochloride crystal- 
lizes in steel-blue needles. The acetyl derivative 
melts at 142. 



Diaminoazobenzene, C 6 H 5 N : 



forms yellow needles, M.P. 117. On reduction it 
yields aniline and triaminobenzene, M.P. 132. 
The hydrochloride of diaminoazobenzene is known 
as ehrysoidine. 

Triaminoazobenzene, NH 2 C 6 H,N:NC 6 H 3 <^ 2 , ( ^, 

JNl2(4:) 

M.P. 143. 

Helianthine, S0 3 HC 6 H 4 N : NC 6 H 4 N(CH 3 ) 2 , forms 
glistening violet leaflets. On reduction it yields 
sulphanilic acid and p-amino-dimethylaniline, M.P. 
41. The sodium salt is known as Methyl Orange. 

The following, which are related to the azo- 
compounds, should also be mentioned. 

Hydrazobenzene, C 6 H 5 NH -NHC 6 H 5 , M.P. 131, 
forms colourless leaflets, which are insoluble in water. 



ORGANIC COMPOUNDS 85 

If its alcoholic solution be exposed to air, azo- 
benzene is produced. Powerful reducing agents 
decompose it into aniline. 

Azoxybenzene, C 6 H 5 N NC 6 H 5 , crystallizes in long 

\/ 


yellow needles, M.P. 36. It is insoluble in water. 
On distillation it decomposes into azobenzene and 
aniline. 

Diazoaminobenzene, C 6 H 5 N : N-NHC 6 H 5 , melts at 
96 and explodes at higher temperatures. 



XXX. PYRIDINE AND 
QUINOLINE GROUP. 

Pyridine, C 5 H 5 N, B.P. 116, has a strong char- 
acteristic odour, and is miscible in all proportions 
with water, alcohol and ether. It forms salts with 
acids. On reduction with sodium and alcohol, 
piperidine is produced. 

Piperidine, CsH^N, B.P. 106, is a colourless liquid 
with a characteristic odour. It is miscible with 
water, alcohol and ether. It is a secondary amine. 

Quinoline, C 9 H 7 N, B.P. 239, is sparingly soluble 
in water. The hydrochloride is crystalline. With 
methyl iodide quinoline forms a yellow crystalline 
compound melting at 72. 



86 THE IDENTIFICATION OF 

XXXI. ALKALOIDS. 

THE alkaloids are nearly all solids, easily soluble in 
alcohol, soluble with difficulty in ether, chloroform 
and benzene, and sparingly soluble or insoluble in 
water. Most are optically active, generally laevo- 
rotatory. They dissolve readily in dilute acids 
with formation of salts, from which the alkaloid is 
precipitated on addition of an alkali. Morphine, 
however, is soluble in excess of sodium hydroxide. 
The following reactions are given by almost all 
the alkaloids : 

1. When an alkaloid is heated in a dry test-tube, 
decomposition takes place with production of a 
smell like burning feathers. 

2. A solution of iodine in potassium iodide pro- 
duces a brown flocculent precipitate in solutions 
of salts of the alkaloids, best when acidified with 
dilute sulphuric acid. 

3. Phosphomolybdic acid l produces a yellow 
precipitate in solutions of all the alkaloids. The 
precipitate is soluble in alkalies and alkaline car- 
bonates. 

4. Potassium mercuric iodide 2 produces a white 
or yellowish white precipitate in solutions of salts 
of alkaloids. The precipitates are insoluble in 
dilute hydrochloric acid. 

5. Aqueous solutions of tannic acid and of picric 
acid precipitate all or nearly all the alkaloids from 
solutions of their salts. 

1 See Appendix. 2 See Appendix. 



ORGANIC COMPOUNDS 87 

CH 3 

CH N 

XX 



HC C HC CJ 

Nicotine, || | is a colour- 

HC CH H 2 C CH 2 , 

\ y 

N 

less oil with an unpleasant smell, B.P. 247. 

Picric acid produces an amorphous precipitate 
which readily crystallizes in small yellow needles 
melting at 218. 

Quinine, when anhydrous melts at 177. The 
normal salts are sparingly soluble, the acid salts 
very soluble. 

Solutions of quinine salts, when acidified with 
sulphuric acid show a fine blue fluorescence. 

Concentrated sulphuric acid dissolves the alkaloid 
to a colourless solution, which on heating turns 
brown and yellow. 

When a solution of a quinine salt is mixed with 
one-fifth of its volume of chlorine water and then 
with an excess of ammonia, an emerald green 
colour is produced. If a little potassium ferro- 
cyanide solution be added after the chlorine water 
and then a few drops of ammonia, the solution 
becomes deep red in colour. 

Cinehonine, M.P. 250. 

When chlorine water and an excess of ammonia 
are added to a solution of a cinchonine salt, a 
yellowish white precipitate is formed. 



88 THE IDENTIFICATION OF 

When potassium ferrocyanide is added to a 
neutral or slightly acid solution of a cinchonine 
salt, a yellowish white flocculent precipitate is 
produced. 

When chlorine water is added drop by drop to a 
solution of a brucine salt, there is produced a red 
colouration which is destroyed by excess of chlorine. 

Strychnine, M.P. 284. 

If a crystal of potassium dichromate be stirred 
in a solution of the alkaloid in concentrated sul- 
phuric acid, there appears a fine blue colour, which 
changes successively to violet, red and reddish 
yellow. 

Potassium ferricyanide and also potassium chro- 
mate produce yellow crystalline precipitates in 
neutral and fairly concentrated solutions of strych- 
nine salts. 

Brucine, when anhydrous melts at 178. 

The solution in concentrated sulphuric acid has 
at first a rose-red colour, which changes to yellow. 

Concentrated nitric acid dissolves brucine and 
its salts giving an intensely red solution, which, 
when warmed, turns yellow. If stannous chloride 
be added to this yellow solution, an intense violet 
colouration is produced. 

Morphine is soluble in dilute acids and in alkalies. 
Its salts dissolve easily in water and alcohol. 

The addition of concentrated nitric acid to the 
solid alkaloid or a salt causes a yellowish red colour 
to appear. 

When ammonium molybdate in concentrated 

I 



ORGANIC COMPOUNDS 89 

sulphuric acid (0-1 gram in a cc.) is placed in a 
porcelain dish and a particle of morphine added 
and crushed with a glass rod, a deep violet colour 
appears, which slowly changes to blue. 

If a few drops of a dilute neutral solution of 
ferric chloride be added to a concentrated solution 
of a morphine salt, a dark blue colouration is 
produced. The colour is destroyed by acids. 

Narcotine, M.P. 176. 

Cold concentrated sulphuric acid dissolves the 
alkaloid, giving a yellow solution. If this be care- 
fully heated in a porcelain dish, the colour changes 
from yellow through orange to red, while a bluish 
violet colour appears at the edges. If the heating 
be continued until the acid begins to evaporate, 
the solution acquires a reddish violet colour. 

If to a solution of narcotine in concentrated 
sulphuric acid there be added 10 to 20 drops sul- 
phuric acid containing a trace of nitric acid, the 
liquid turns brown and then quickly red. 



XXXII. SULPHUR COMPOUNDS. 

(OTHER THAN SULPHONIC ACIDS AND 
DERIVATIVES.) 

Carbon Bisulphide, CS 2 , is a highly refractive colour- 
less liquid boiling at 47. When it is added to 
alcoholic potash, potassium xanthate is precipitated 
in yellow needles 

I 



90 THE IDENTIFICATION OP 

^OC 2 H 5 
CS 2 + KOH + C 2 H 5 OH = CS + H 2 0. 



MERCAPTANS OR THIO-ALCOHOLS. 

These are colourless liquids with a disagreeable 
garlic-like odour, and are insoluble in water. 

1. Oxidation with nitric acid produces sulphonic 
acids which can be identified by conversion into their 
amides (see page 48). 

2. When a mercaptan is added to a few cc. of an 
alcoholic solution of mercuric chloride, a white 
precipitate is formed. 

3. When sodium is added to a mercaptan in 
ethereal solution, hydrogen is evolved and the 
sodium salt crystallizes in white needles. 

Ethyl mercaptan, C 2 H 5 SH, B.P. 36. 
rc-Propyl mercaptan, C 3 H 7 SH, B.P. 68. 
Isopropyl mercaptan, (CH 3 ) 2 CHSH, B.P. 59. 

THIOETHERS OR ALKYL SULPHIDES. 

The thioethers are colourless liquids with a 
disagreeable odour, insoluble in water, but easily 
soluble in alcohol and ether. They are characterized 
by their additive powers ; for example, they unite 
with alkyl iodides to form sulphine iodides. 

One cc. ethyl iodide is added to 1 cc. of the 
thioether and the mixture warmed. After adding 
about a gram of moist silver oxide, the mixture is 

' 



ORGANIC COMPOUNDS 91 

shaken with water, again warmed and filtered. 
The filtrate will be strongly alkaline owing to the 
presence of trialkyl sulphoxide. 

R 2 g + C 2 H 5 I =R 2 EtSI 

R 2 EtSI + AgOH = R 2 EtS-OH + Agl. 

Methyl sulphide, (CH 3 ) 2 S 3 B.P. 37-5. 

Ethyl sulphide, (C 2 H 5 ) 2 S, B.P. 92. 

n-Propyl Sulphide, (C 3 H 7 ) 2 S, B.P. 130-135. 

Allyl Sulphide, (CH 3 -CH : CH) 2 S, B.P. 139-140, 
forms a crystalline precipitate with alcoholic 
mercuric chloride. 

Thiophene, C 4 H 4 S, B.P. 84. 

When a crystal of isatin is dissolved in 2 cc. 
cone, sulphuric acid, and to this solution a few 
drops of thiophene are added, a deep blue colour is 
produced. 

COMPOUNDS CONTAINING NITROGEN AND 
SULPHUR. 

MUSTARD OILS OR ISOTHIOCYANATES. 

These are liquids with a very penetrating odour. 
They are insoluble in water. Their boiling points 
are lower than those of the corresponding thio- 
cyanates. 

1. When heated to 100 with concentrated 
hydrochloric acid under a reflux condenser, they 
are decomposed into amines, sulphuretted hydrogen 
and carbon dioxide 

R-NCS +2H 2 =R-NH 2 +C0 2 +H 2 S. 



v 



92 THE IDENTIFICATION OF 

2. Reduction by means of zinc and hydrochloric 
acid produces an amine and thiof ormaldehyde, which 
has an odour of onions 

R-NCS + 2H 2 = R-NH 2 + H-CHS. 

3. One cc. of the mustard oil is warmed with one 
cc. aniline for a few minutes. On cooling, a 
thiourea crystallizes out, and its melting point is 
determined (see p. 93). 



+ C 6 H 5 NH 2 = CS 



4. If 1 cc. of the mustard oil be heated with one 
gram yellow mercuric oxide, an isocyanate and a 
black precipitate of mercuric sulphide are formed. 

Methyl mustard oil, CSNCH 3 , M.P. 35. 

Ethyl mustard oil, CSNC 2 H 5 , B.P. 131-132. 

Allyl mustard oil, CSNC 3 H 5 , B.P. 150-7. 

Phenyl mustard oil, CSNC 6 H 5 , B.P. 222, when 
reduced with zinc dust gives benzonitrile. 

THIOUREAS. 

When a thiourea is heated with concentrated 
hydrochloric acid under a reflux condenser for 
some time and then distilled, the distillate contains 
a mustard oil. If the residue, which contains a 
guanidine derivative, be heated with concentrated 
caustic soda solution, an amine and a carbonate 
are produced. 



(a) CS =RNCS+R-NH 3 



ORGANIC COMPOUNDS 93 



(6) CS +RNH 2 = C = NR + H 2 S 

XKTHR 



(c) CNR +2NaOH+H 2 0=3R-NH 2 +Na 2 C0 3 . 



Thiourea, CS , M.P. 172, when boiled with 



alkalies, hydrochloric acid or sulphuric acid, is 
decomposed. 



CS + 2H 2 = C0 2 + 2NH 3 + H 2 S. 
\NH 2 

^NHCH 3 

Methylthiourea, CS , M.P. 118. 

^NH 2 

^NHCH 3 

Dimethylthiourea, CS , M.P. 51-5. 

^NHCH 3 

^NHC 2 H 5 

Ethylthiourea, CS , M.P. 113. 

\NH 2 

^-NHC 2 H 5 

Diethylthiourea, CS , M.P. 77. 

\NHC 2 H 5 

^NHCH 2 CH:CH 2 

Allylthiourea, CS , M.P. 78-5 

^-NH 2 

^NHC 6 H 5 
Phenylthiourea, CS , M.P. 154. 



I 



94 THE IDENTIFICATION OF 

^NHC 6 H 6 

/Stym-Diphenylthiourea, CS , M.P. 151 

\NHC 6 H 5 

^NHC 6 H 5 
Phenylmethylthiourea, CS , M.P. 113. 

\NHCH 3 
^NHC 6 H 5 
Phenylethylthiourea, CS , M.P. 99-5. 



THIOCYANATES. 

1. When a thiocyanate is reduced with zinc dust 
and hydrochloric acid, a mercaptan and hydrocyanic 
acid 1 are produced 

CNSR + H 2 = CNH + R-SH. 

2. Boiling nitric acid oxidizes thiocyanates to 
alkyl sulphonic acids. 

Methyl thiocyanate, CNSCH 3 , B.P. 133. 
Ethyl thioeyanate, CNSC 2 H 5 , B.P. 142. 
Allyl thiocyanate, CNSC 3 H 5 , B.P. 161, rapidly 
changes on boiling to the isomeric mustard oil. 



XXXIII. TERPENES AND 
ALLIED COMPOUNDS. 

THESE compounds, although possessing many of 
the properties of compounds already considered, 
have distinctive characteristics, thus necessitating 

1 Since hydrocyanic acid is a poison, great care must be 
taken in carrying out this reaction. 



OEGANIC COMPOUNDS 95 

their separate classification. They are neither 
aliphatic nor aromatic, and are complex in structure. 
Nevertheless, they yield characteristic derivatives 
which as a general rule can be easily identified. They 
are all highly inflammable, possess characteristic 
odours and are insoluble in water, but are readily 
soluble in most organic solvents. 



HYDROCARBONS. 

Dipentene, C 10 H 16 , B.P. 175-176. The dihydro- 
Moride, Ci H 16 '2HCl, is prepared by passing dry 
hydrochloric acid over a few cc. dipentene for 
about one hour. The dihydrochloride separates on 
pouring the mixture on ice. It is dried on a 
porous plate and recrystallized from alcohol. M.P. 
48-50. 

Dipentene tetrabromide, Ci H 16 Br 4 , can be made 
by adding bromine to a chloroform solution of 
dipentene, cooled to -10 by salt and ice. The 
chloroform is removed by blowing a current of dry 
air through the solution. The tetrabromide on 
recrystallization from ethyl acetate, melts at 125. 

The active forms of dipentene are the limonenes. 
The active tetrabromides melt at 104. 

Pinene, C 10 H 16 , B.P. 155-156. 

The nitrosochloride, C 10 H 16 NOC1, melts at 115. 
It is prepared by adding 1-5 cc. 33 per cent, hydro- 
chloric acid to a mixture (cooled in ice) of 5 grams 
pinene, 5 grams glacial acetic acid, and 5 grams 
ethyl nitrite. After a short time the nitrosochloride 



96 THE IDENTIFICATION OF 

separates in large crystals. It is filtered off at the 
pump and washed with alcohol. 

Camphene, C 10 H 16 , melts at 51. 

When heated with glacial acetic acid and a little 
sulphuric acid, camphene forms isobornyl acetate. 
On adding water the ester separates as an oil. It 
is hydrolysed with alcoholic caustic potash, the 
alcohol removed, and isoborneol is precipitated on 
addition of water. Isoborneol melts about 208 in 
a closed tube. 

Menthene, C 10 H 18 , B.P. 167-168. The nitroso- 
chloride melts at 127. 

ALCOHOLS. 

Terpineol, d H 17 OH, melts at 35. It forms a 
nitrosochloride melting at 112-113. 

Borneol, C 10 H 17 OH, M.P. 203-204, and Iso- 
borneol, C 10 H 17 OH, M.P. 208, yield derivatives of 
very similar melting and boiling points. The 
phenylurethanes of both melt at 138-139. 

PREPARATION OF APHENYLURETHANE. Molecular 
quantities of the alcohol and phenyl isocyanate 1 
are mixed and heated rapidly to boiling. The mix- 
ture is well shaken and allowed to stand, the flask 
being closed with a calcium chloride tube. The 
unchanged phenyl isocyanate is extracted with 
benzene, and the residual urethane, after removal 
of benzene, is washed with cold water and re- 
crystallized from ethyl acetate or a mixture of 

1 This preparation should be carried out in a draught- 
cupboard. 



ORGANIC COMPOUNDS 97 

ether and petroleum ether. (Solvents containing 
"hydroxyl" should be avoided.) 

When isoborneol is heated for some time with 
ethyl alcohol and concentrated sulphuric acid, iso- 
bornyl ethyl ether (B.P. 203-204) is produced. 
Bornyl ethyl ether is not formed in this way. 

Menthol, C 10 H 19 OH, M.P. 42. The phenyl- 
urethane forms needles, melting at 111. 

KETONES. 

Carvone, C 10 H 14 0, B.P. 223-224. On heating 
with a little acid it is converted into carvacrol. 

Camphor, C 10 H 16 0, M.P. 177-178. The oxime 
melts at 120 ; the semicarbazone at 236. 

Menthone, C 10 H 18 0, B.P. 208, has a peppermint- 
like odour. The semicarbazone melts at 184. 



XXXIV. ALBUMINS AND 
PROTEIDS. 

THESE are compounds of very complicated structure, 
and, with a few exceptions, do not crystallize. They 
are insoluble in the common organic solvents, but 
dissolve in aqueous solutions of acids and alkalies. 
The following are general tests for the albumins : 
I. MILLON'S KB AGENT (a solution of mercuric 
nitrate containing nitrous acid) gives an intense red 
colouration on heating. 

H 



98 

II. XANTHO-PROTEIN REACTION. By heating 
an albumin with fairly concentrated nitric acid, 
there separates a yellow flocculent precipitate 
of xanthoproteic acid, which dissolves in alkali 
giving an orange red solution. 

III. BIURET REACTION. When caustic potash is 
added to albumin, and then a very dilute solution 
of copper sulphate drop by drop, a fine violet- 
red colouration appears. 

Egg-albumin is soluble in water and is precipitated 
from its solutions by metaphosphoric acid and by 
acetic acid. The precipitate is soluble in excess 
of the latter. Egg-albumin treated with con- 
centrated sulphuric acid and sugar solution gives 
a red solution which changes to violet-red. 

Casein contains phosphorus. An alkaline solu- 
tion of casein dissolves cupric hydrate, giving a 
violet colour. 

Gelatine contains sulphur. It is precipitated 
from its solutions by tannin. 



Appendix. 



MELTING-POINT APPARATUS. The^ sketch shows an 
apparatus which is very convenient "and gives very 




3-3 cms. 



Il-Scms. 



4 cms. 



4-8cms 



accurate determinations. 

SPECIAL REAGENTS. 

NEUTRAL FERRIC CHLORIDE SOLUTION. To some of 
the ferric chloride solution provided in the laboratory r 
dilute ammonium hydroxide or ammonium carbonate 
is added drop by drop until a precipitate just begins to* 
form. 

SCHIFF'S REAGENT. Sulphurous acid is added to a 
dilute solution of rosaniline hydrochloride (magenta) 
until the colour just disappears. 



100 APPENDIX 

FEHLING'S SOLUTION. (I) 35 grams copper sulphate 
are dissolved in water and diluted to 1 litre. (2) 173 
grams sodium potassium tartrate (Rochelle salt) and 70 
.grams caustic soda are dissolved in water and diluted 
to 1 litre. 

These solutions are kept in separate bottles. Equal 
volumes of each are mixed immediately before making 
a test. 

SOLUTION OF IODINE IN POTASSIUM IODIDE. 5 grams 
of iodine are dissolved in water containing 10 grams of 
potassium iodide and the solution made up to 1 litre. 
HYDRIODIC ACID. To obtain the constant boiling 
solution (Sp. Gr. 1-7) hydriodic acid of Sp. Gr. 2-00 is 
diluted with an equal volume of water and distilled over 
a small quantity of red phosphorus. The fraction 
boiling at 125-126 is collected separately. 

SODIUM BISULPHITE (saturated solution). Sulphur 
dioxide is passed into a saturated solution of sodium 
carbonate for some time. Solid carbonate is added, 
from time to time, until no more dissolves. The final 
solution should smell strongly of sulphur dioxide. 

PHOSPHOMOLYBDIC ACID. To a solution of 75 grams 
ammonium molybdate in 500 cc. nitric acid (Sp. Gr. 1-2) 
,and 500 cc. water, sodium phosphate solution is added 
until there is no further precipitate. This is then filtered 
off, well washed and finally warmed with sodium car- 
bonate solution until completely dissolved. The solu- 
tion is evaporated to dryness, and the residue ignited. 
The product is warmed with water and dissolved in 
a considerable excess of nitric acid. 

POTASSIUM MERCURIC IODIDE. 13 grams mercuric 
chloride and 50 grams potassium iodide are dissolved hi 
water and the mixture made up to 1 litre. 

MILLON'S REAGENT. A small quantity of mercury is 
dissolved in twice its weight of concentrated nitric acid 
in the cold and twice its volume of water is added. 




INDEX 



A. 

Acetyl compounds of 
amines, preparation of 

Acid amides .... 

Acid anhydrides. 

Acid anilides 

Acid halides .... 

Acid imides .... 

Acids, aliphatic mono- 
basic saturated 

Acids, aliphatic poly- 
basic saturated . 

Acids, aliphatic unsatu- 
rated 

Acids, amino. 

Acids, aromatic . 

Acids, aromatic sulphonic 

Acids, halogen substi- 
tuted 

Acids, hydroxy . 

Acids, nitro .... 

Albumins 

Alcohol phenols . 

Alcohols, polyhydric 

Alcohols, primary mono- 
hydric 

Alcohols, secondary mono- 
hydric 

Alcohols, tertiary mono- 
hydric 

Aldehyde ethers 

Aldehyde group, detec- 
tion of . 



PAGE p AGEr 

Aldehydes .... 29 

Aldehydes substituted . 33 

Alkaloids 8$ 

Alkyl sulphides ... 90 

Amines, aliphatic . . 62 

Amines, aromatic . . 64 

Amines, halogen . 67 
Amino group, detection 

of 11 

Aminophenols ... 29 

Azo compounds ... 83 

Azo group, detection of 14 

B. 

Biuret reaction ... 76- 

C. 

Carbohydrates ... 60 
Chromic acid oxidation 

mixture 15> 

D. 

Diazonium salt, prepara- 
tion of 64 



65 
53 
52 
55 
53 
55 

38 
39 

40 
46 
41 

48 

45 
43 
46 
97 
27 
21 

19 
21 

21 
36 



E. 

Esters 56 

Ethers 22 

Ethoxy group, detection 

of * 9 



101 



102 



INDEX 



PAGE 



M. 



Fehling's solution, pre- 
paration of ... 
Ferric chloride, neutral 
solution 

G. 
Glucosides .... 

H. 


99 
99 

61 


Melting-point apparatus 
Mendius' reaction . 13 
Mercaptans .... 
Methoxy group, detec- 
tion of 
Millon's reagent, prepara- 
tion of 
Mustard oils .... 

N. 
Nitriles . . 


99 
,74 

90 

9 

100 
91 

74 


Halogen compounds, ali- 


80 


Nitriles, detection of . 


13 


Halogen compounds, aro- 
matic 
Halogen phenols. 
Hydriodic acid, constant 


81 

27 

100 


Nitro compounds, ali- 
phatic 
Nitro compounds, aro- 
matic 
Nitro group, detection of 


68 

69 
3 


Hydrocarbons, aliphatic 
Hydrocarbons, aromatic 
Hydroxyl group, detec- 
tion of 

I. 

Tmino group, detection of 
Iodine in potassium io- 


14 
15 

8 

12 

100 


Nitroanilines .... 
Nitro-ketones 
Nitrophenols .... 
Nitroso compounds . 
Nitrosochloride, prepara- 
tion of a . 

0. 

Oxidation with chromic 


71 
71 

70 

72 

95 
18 


Isocyanates .... 
Isonitriles 
Jsonitriles, detection of . 
Jsothiocyanates . 

K. 

Ketone group, detection 
of 


75 
74 
13 
91 

11 


Oximes, preparation of 

P. 
Phenols 
Phenols, alcohol . 
Phenols, halogen 
Phenylhydrazones, pre- 
paration of ... 


29 

23 

27 
27 

30 


.Ketones . . . 


36 


Phenylurethanes, pre- 




Ketones, nitro- . 

L. 

Liebermann's test . 


71 
12 


paration of ... 
Phosphomolybdic acid, 
preparation of ' . 
Picrates, preparation of 
Piperidine .... 


96 

100 
17 

86 



INDEX 



103 



PAGE 

Potassium mercuric io- 
dide, preparation of . 100 

Proteids 97 

Pyridine 85 

Q. 

Quinoline 85 

Quinones 58 

S. 

Schiffs reaction ... 10 

Schiff's reagent, prepara- 
tion of 99 

Schotten-Baumann reac- 
tion 8 

Semicarbazones, prepar- 
ation of .... 30 

Sodium bisulphite, pre- 
paration of . . . 100 

SuJphonamides, prepara- 
tion of . 48 



PAGE 

Sulphur compounds. . 89 



T. 

Terpenes 94 

Tests for elements . . 4 

Tests, preliminary . . 1 

Thioalcohols .... 90 

Thiocyanates . ... 94 

Thio-ethers .... 90 

Thiophene .... 91 

Thioureas 92 

Tollen's reaction . 9 



U. 

Ureas 75 

Ureides 75 

Unsaturation, tests for 4 

Uric acid group ... 78 



Butler & Tanner. 'The Selwood Printing Works, Frome, anc 



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14 DAY USE 

N TO DESK FROM WHICH BORROWED 

LOAN DEPT. 







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